Added new `ui.dialogs` module for more user-friendly dialog support.

As a result, removed `ui.filteredlist()` and changed `io.open_file()` and
`io.snapopen()` APIs to accept tables of files and paths instead of "\n"
delimited strings.

3 files changed, 538 insertions, 116 deletions

diff --git a/core/.ui.dialogs.luadoc b/core/.ui.dialogs.luadoc
new file mode 100644
index 00000000..dc3e99e8
--- /dev/null
+++ b/core/.ui.dialogs.luadoc
@@ -0,0 +1,415 @@
+-- Copyright 2007-2013 Mitchell mitchell.att.foicica.com. See LICENSE.
+-- This is a DUMMY FILE used for making LuaDoc for built-in functions in the
+-- ui.dialogs table.
+
+--- Provides a set of interactive dialog prompts for user input.
+module('ui.dialogs')
+
+---
+-- Prompts the user with a generic message box dialog defined by dialog options
+-- table *options*, returning the index of the selected button or, if
+-- *options*.`string_output` is `true`, the selected button's label.
+-- If the dialog timed out, returns `0` or `"timeout"`. If the user canceled the
+-- dialog, returns `-1` or `"delete"`.
+-- @param options Table of key-value option pairs for the message box.
+--
+--   * `title`: The dialog's title text.
+--   * `text`: The dialog's main message text.
+--   * `informative_text`: The dialog's extra informative text.
+--   * `icon`: The dialog's GTK stock icon name. Examples are
+--     "gtk-dialog-error", "gtk-dialog-info", "gtk-dialog-question", and
+--     "gtk-dialog-warning". The dialog does not display an icon by default.
+--   * `icon_file`: The dialog's icon file path. This option has no effect when
+--     `icon` is set.
+--   * `button1`: The right-most button's label. The default value is
+--     `_L['_OK']`.
+--   * `button2`: The middle button's label.
+--   * `button3`: The left-most button's label. This option requires `button2`
+--     to be set.
+--   * `string_output`: Return the selected button's label or the dialog's exit
+--     status instead of the button's index or the exit code. The default value
+--     is `false`.
+--   * `width`: The pixel width of the dialog.
+--   * `height`: The pixel height of the dialog.
+--   * `float`: Show the dialog on top of all desktop windows. The default value
+--     is `false`.
+--   * `timeout`: The number of seconds the dialog waits for the user to select
+--     a button before timing out. Dialogs do not time out by default.
+-- @return selected button or exit code
+-- @usage ui.dialogs.msgbox{title = 'EOL Mode', text = 'Which EOL?',
+--   icon = 'gtk-dialog-question', button1 = 'CRLF', button2 = 'CR',
+--   button3 = 'LF'}
+function msgbox(options) end
+
+---
+-- Prompts the user with a generic message box dialog defined by dialog options
+-- table *options* and with localized "Ok" and "Cancel" buttons, returning the
+-- index of the selected button or, if *options*.`string_output` is `true`, the
+-- selected button's label.
+-- If the dialog timed out, returns `0` or `"timeout"`. If the user canceled the
+-- dialog, returns `-1` or `"delete"`.
+-- @param options Table of key-value option pairs for the message box.
+--
+--   * `title`: The dialog's title text.
+--   * `text`: The dialog's main message text.
+--   * `informative_text`: The dialog's extra informative text.
+--   * `icon`: The dialog's GTK stock icon name. Examples are
+--     "gtk-dialog-error", "gtk-dialog-info", "gtk-dialog-question", and
+--     "gtk-dialog-warning". The dialog does not display an icon by default.
+--   * `icon_file`: The dialog's icon file path. This option has no effect when
+--     `icon` is set.
+--   * `no_cancel`: Do not display the "Cancel" button. The default value is
+--     `false`.
+--   * `string_output`: Return the selected button's label or the dialog's exit
+--     status instead of the button's index or the exit code. The default value
+--     is `false`.
+--   * `width`: The pixel width of the dialog.
+--   * `height`: The pixel height of the dialog.
+--   * `float`: Show the dialog on top of all desktop windows. The default value
+--     is `false`.
+--   * `timeout`: The number of seconds the dialog waits for the user to select
+--     a button before timing out. Dialogs do not time out by default.
+-- @return selected button or exit code
+function ok_msgbox(options) end
+
+---
+-- Prompts the user with a generic message box dialog defined by dialog options
+-- table *options* and with localized "Yes", "No", and "Cancel" buttons,
+-- returning the index of the selected button or, if *options*.`string_output`
+-- is `true`, the selected button's label.
+-- If the dialog timed out, returns `0` or `"timeout"`. If the user canceled the
+-- dialog, returns `-1` or `"delete"`.
+-- @param options Table of key-value option pairs for the message box.
+--
+--   * `title`: The dialog's title text.
+--   * `text`: The dialog's main message text.
+--   * `informative_text`: The dialog's extra informative text.
+--   * `icon`: The dialog's GTK stock icon name. Examples are
+--     "gtk-dialog-error", "gtk-dialog-info", "gtk-dialog-question", and
+--     "gtk-dialog-warning". The dialog does not display an icon by default.
+--   * `icon_file`: The dialog's icon file path. This option has no effect when
+--     `icon` is set.
+--   * `no_cancel`: Do not display the "Cancel" button. The default value is
+--     `false`.
+--   * `string_output`: Return the selected button's label or the dialog's exit
+--     status instead of the button's index or the exit code. The default value
+--     is `false`.
+--   * `width`: The pixel width of the dialog.
+--   * `height`: The pixel height of the dialog.
+--   * `float`: Show the dialog on top of all desktop windows. The default value
+--     is `false`.
+--   * `timeout`: The number of seconds the dialog waits for the user to select
+--     a button before timing out. Dialogs do not time out by default.
+-- @return selected button or exit code
+function yesno_msgbox(options) end
+
+---
+-- Prompts the user with a one-line input box dialog defined by dialog options
+-- table *options*, returning the index of the selected button along with the
+-- input text or, if *options*.`string_output` is `true`, the selected button's
+-- label along with the input text.
+-- If the dialog timed out, returns `0` or `"timeout"`. If the user canceled the
+-- dialog, returns `-1` or `"delete"`.
+-- @param options Table of key-value option pairs for the input box.
+--
+--   * `title`: The dialog's title text.
+--   * `informative_text`: The dialog's main message text.
+--   * `text`: The dialog's initial input text.
+--   * `button1`: The right-most button's label. The default value is
+--     `_L['_OK']`.
+--   * `button2`: The middle button's label.
+--   * `button3`: The left-most button's label. This option requires `button2`
+--     to be set.
+--   * `string_output`: Return the selected button's label or the dialog's exit
+--     status instead of the button's index or the exit code. The default value
+--     is `false`.
+--   * `width`: The pixel width of the dialog.
+--   * `height`: The pixel height of the dialog.
+--   * `float`: Show the dialog on top of all desktop windows. The default value
+--     is `false`.
+--   * `timeout`: The number of seconds the dialog waits for the user to select
+--     a button before timing out. Dialogs do not time out by default.
+-- @return selected button or exit code, input text
+-- @usage ui.dialogs.inputbox{title = 'Goto Line', informative_text = 'Line:',
+--   text = '1'}
+function inputbox(options) end
+
+---
+-- Prompts the user with a one-line input box dialog defined by dialog options
+-- table *options* and with localized "Ok" and "Cancel" buttons, returning the
+-- index of the selected button along with the input text or, if
+-- *options*.`string_output` is `true`, the selected button's label along with
+-- the input text.
+-- If the dialog timed out, returns `0` or `"timeout"`. If the user canceled the
+-- dialog, returns `-1` or `"delete"`.
+-- @param options Table of key-value option pairs for the input box.
+--
+--   * `title`: The dialog's title text.
+--   * `informative_text`: The dialog's main message text.
+--   * `text`: The dialog's initial input text.
+--   * `no_cancel`: Do not display the "Cancel" button. The default value is
+--     `false`.
+--   * `string_output`: Return the selected button's label or the dialog's exit
+--     status instead of the button's index or the exit code. The default value
+--     is `false`.
+--   * `width`: The pixel width of the dialog.
+--   * `height`: The pixel height of the dialog.
+--   * `float`: Show the dialog on top of all desktop windows. The default value
+--     is `false`.
+--   * `timeout`: The number of seconds the dialog waits for the user to select
+--     a button before timing out. Dialogs do not time out by default.
+-- @return selected button or exit code, input text
+function standard_inputbux(options) end
+
+---
+-- Prompts the user with a one-line masked input box dialog defined by dialog
+-- options table *options*, returning the index of the selected button along
+-- with the input text or, if *options*.`string_output` is `true`, the selected
+-- button's label along with the input text.
+-- If the dialog timed out, returns `0` or `"timeout"`. If the user canceled the
+-- dialog, returns `-1` or `"delete"`.
+-- @param options Table of key-value option pairs for the input box.
+--
+--   * `title`: The dialog's title text.
+--   * `informative_text`: The dialog's main message text.
+--   * `text`: The dialog's initial input text.
+--   * `button1`: The right-most button's label. The default value is
+--     `_L['_OK']`.
+--   * `button2`: The middle button's label.
+--   * `button3`: The left-most button's label. This option requires `button2`
+--     to be set.
+--   * `string_output`: Return the selected button's label or the dialog's exit
+--     status instead of the button's index or the exit code. The default value
+--     is `false`.
+--   * `width`: The pixel width of the dialog.
+--   * `height`: The pixel height of the dialog.
+--   * `float`: Show the dialog on top of all desktop windows. The default value
+--     is `false`.
+--   * `timeout`: The number of seconds the dialog waits for the user to select
+--     a button before timing out. Dialogs do not time out by default.
+-- @return selected button or exit code, input text
+function secure_inputbox(options) end
+
+---
+-- Prompts the user with a one-line masked input box dialog defined by dialog
+-- options table *options* and with localized "Ok" and "Cancel" buttons,
+-- returning the index of the selected button along with the input text or, if
+-- *options*.`string_output` is `true`, the selected button's label along with
+-- the input text.
+-- If the dialog timed out, returns `0` or `"timeout"`. If the user canceled the
+-- dialog, returns `-1` or `"delete"`.
+-- @param options Table of key-value option pairs for the input box.
+--
+--   * `title`: The dialog's title text.
+--   * `informative_text`: The dialog's main message text.
+--   * `text`: The dialog's initial input text.
+--   * `no_cancel`: Do not display the "Cancel" button. The default value is
+--     `false`.
+--   * `string_output`: Return the selected button's label or the dialog's exit
+--     status instead of the button's index or the exit code. The default value
+--     is `false`.
+--   * `width`: The pixel width of the dialog.
+--   * `height`: The pixel height of the dialog.
+--   * `float`: Show the dialog on top of all desktop windows. The default value
+--     is `false`.
+--   * `timeout`: The number of seconds the dialog waits for the user to select
+--     a button before timing out. Dialogs do not time out by default.
+-- @return selected button or exit code, input text
+function secure_standard_inputbox(options) end
+
+---
+-- Prompts the user with a file selection dialog defined by dialog options
+-- table *options*, returning the string file selected or, if
+-- *options*.`select_multiple` is `true`, the list of files selected.
+-- If the user canceled the dialog, returns `nil`.
+-- @param options Table of key-value option pairs for the dialog.
+--
+--   * `title`: The dialog's title text.
+--   * `with_directory`: The initial filesystem directory to show.
+--   * `with_file`: The initially selected filename. This option requires
+--     `with_directory` to be set.
+--   * `with_extension`: The list of extensions selectable files must have.
+--   * `select_multiple`: Allow the user to select multiple files. The default
+--     value is `false`.
+--   * `select_only_directories`: Only allow the user to select directories. The
+--     default value is `false`.
+-- @return filename, list of filenames, or nil
+-- @usage ui.dialogs.fileselect{title = 'Open C File', with_directory = _HOME,
+--   with_extension = {'c', 'h'}, select_multiple = true}
+function fileselect(options) end
+
+---
+-- Prompts the user with a file save dialog defined by dialog options table
+-- *options*, returning the string file chosen.
+-- If the user canceled the dialog, returns `nil`.
+-- @param options Table of key-value option pairs for the dialog.
+--
+--   * `title`: The dialog's title text.
+--   * `with_directory`: The initial filesystem directory to show.
+--   * `with_file`: The initially chosen filename. This option requires
+--     `with_directory` to be set.
+--   * `with_extension`: The list of extensions selectable files must have.
+--   * `no_create_directories`: Prevent the user from creating new directories.
+--     The default value is `false`.
+-- @return filename or nil
+function filesave(options) end
+
+---
+-- Prompts the user with a multiple-line textbox dialog defined by dialog
+-- options table *options*, returning the index of the selected button along
+-- with the textbox text if *options*.`editable` is `true` or, if
+-- *options*.`string_output` is `true`, the selected button's label along with
+-- the textbox text if *options*.`editable` is also `true`.
+-- If the dialog timed out, returns `0` or `"timeout"`. If the user canceled the
+-- dialog, returns `-1` or `"delete"`.
+-- @param options Table of key-value option pairs for the dialog.
+--
+--   * `title`: The dialog's title text.
+--   * `informative_text`: The dialog's main message text.
+--   * `text`: The dialog's initial textbox text.
+--   * `text_from_file`: The filename whose contents are loaded into the
+--     textbox. This option has no effect when `text` is given.
+--   * `button1`: The right-most button's label. The default value is
+--     `_L['_OK']`.
+--   * `button2`: The middle button's label.
+--   * `button3`: The left-most button's label. This option requires `button2`
+--     to be set.
+--   * `editable`: Allows the user to edit the text in the textbox. The default
+--     value is `false`.
+--   * `focus_textbox`: Focus the textbox instead of the dialog buttons. The
+--     default value is `false`.
+--   * `scroll_to`: Where to scroll the textbox text when it is not all visible.
+--     The available values are `"top"` and `"bottom"`. The default value is
+--     `"top"`.
+--   * `selected`: Select all textbox text. The default value is `false`.
+--   * `monospaced_font`: Use a monospaced font in the textbox instead of a
+--     proportional one. The default value is `false`.
+--   * `string_output`: Return the selected button's label or the dialog's exit
+--     status instead of the button's index or the exit code. The default value
+--     is `false`.
+--   * `width`: The pixel width of the dialog.
+--   * `height`: The pixel height of the dialog.
+--   * `float`: Show the dialog on top of all desktop windows. The default value
+--     is `false`.
+--   * `timeout`: The number of seconds the dialog waits for the user to select
+--     a button before timing out. Dialogs do not time out by default.
+-- @return selected button or exit code, textbox text
+-- @usage ui.dialogs.textbox{title = 'License Agreement',
+--   informative_text = 'You agree to:', text_from_file = _HOME..'/LICENSE'}
+function textbox(options) end
+
+---
+-- Prompts the user with a drop down item selection dialog defined by dialog
+-- options table *options*, returning the index of the selected button along
+-- with the index of the selected item or, if *options*.`string_output` is
+-- `true`, the selected button's label along with the selected item's text.
+-- If *options*.`exit_onchange` closed the dialog, returns `4` along with either
+-- the index of the selected item or the selected item's text. If the dialog
+-- timed out, returns `0` or `"timeout"`. If the user canceled the dialog,
+-- returns `-1` or `"delete"`.
+-- @param options Table of key-value option pairs for the drop down dialog.
+--
+--   * `title`: The dialog's title text.
+--   * `text`: The dialog's main message text.
+--   * `items`: The list of string items to show in the drop down.
+--   * `button1`: The right-most button's label. The default value is
+--     `_L['_OK']`.
+--   * `button2`: The middle button's label.
+--   * `button3`: The left-most button's label. This option requires `button2`
+--     to be set.
+--   * `exit_onchange`: Close the dialog after selecting a new item. The default
+--     value is `false`.
+--   * `select`: The index of the initially selected list item. The default
+--     value is `1`.
+--   * `string_output`: Return the selected button's label or the dialog's exit
+--     status along with the selected item's text instead of the button's index
+--     or the exit code along with the item's index. The default value is
+--     `false`.
+--   * `width`: The pixel width of the dialog.
+--   * `height`: The pixel height of the dialog.
+--   * `float`: Show the dialog on top of all desktop windows. The default value
+--     is `false`.
+--   * `timeout`: The number of seconds the dialog waits for the user to select
+--     a button before timing out. Dialogs do not time out by default.
+-- @return selected button or exit code, selected item
+-- @usage ui.dialogs.dropdown{title = 'Select Encoding', width = 200,
+--   items = io.encodings, string_output = true}
+function dropdown(options) end
+
+---
+-- Prompts the user with a drop down item selection dialog defined by dialog
+-- options table *options* and with localized "Ok" and "Cancel" buttons,
+-- returning the index of the selected button along with the index of the
+-- selected item or, if *options*.`string_output` is `true`, the selected
+-- button's label along with the selected item's text.
+-- If *options*.`exit_onchange` closed the dialog, returns `4` along with either
+-- the index of the selected item or the selected item's text. If the dialog
+-- timed out, returns `0` or `"timeout"`. If the user canceled the dialog,
+-- returns `-1` or `"delete"`.
+-- @param options Table of key-value option pairs for the drop down dialog.
+--
+--   * `title`: The dialog's title text.
+--   * `text`: The dialog's main message text.
+--   * `items`: The list of string items to show in the drop down.
+--   * `no_cancel`: Do not display the "Cancel" button. The default value is
+--     `false`.
+--   * `exit_onchange`: Close the dialog after selecting a new item. The default
+--     value is `false`.
+--   * `select`: The index of the initially selected list item. The default
+--     value is `1`.
+--   * `string_output`: Return the selected button's label or the dialog's exit
+--     status along with the selected item's text instead of the button's index
+--     or the exit code along with the item's index. The default value is
+--     `false`.
+--   * `width`: The pixel width of the dialog.
+--   * `height`: The pixel height of the dialog.
+--   * `float`: Show the dialog on top of all desktop windows. The default value
+--     is `false`.
+--   * `timeout`: The number of seconds the dialog waits for the user to select
+--     a button before timing out. Dialogs do not time out by default.
+-- @return selected button or exit code, selected item
+function standard_dropdown(options) end
+
+---
+-- Prompts the user with a filtered list item selection dialog defined by dialog
+-- options table *options*, returning the index of the selected button along
+-- with the index(es) of the selected item(s) (depending on whether or not
+-- *options*.`select_multiple` is `true`) or, if *options*.`string_output` is
+-- `true`, the selected button's label along with the selected item's or items'
+-- text.
+-- If the dialog timed out, returns `0` or `"timeout"`. If the user canceled the
+-- dialog, returns `-1` or `"delete"`.
+-- Spaces in the filter text are treated as wildcards.
+-- @param options Table of key-value option pairs for the drop down dialog.
+--
+--   * `title`: The dialog's title text.
+--   * `text`: The dialog's main message text.
+--   * `columns`: The list of string column names for list rows.
+--   * `items`: The list of string items to show in the drop down.
+--   * `button1`: The right-most button's label. The default value is
+--     `_L['_OK']`.
+--   * `button2`: The middle button's label.
+--   * `button3`: The left-most button's label. This option requires `button2`
+--     to be set.
+--   * `select_multiple`: Allow the user to select multiple items. The default
+--     value is `false`.
+--   * `search_column`: The column number to filter the input text against. The
+--     default value is `1`. This option requires `columns` to be set and
+--     contain at least *n* column names.
+--   * `output_column`: The column number to use for `string_output`. The
+--     default value is `1`. This option requires `columns` to be set and
+--     contain at least *n* column names.
+--   * `string_output`: Return the selected button's label or the dialog's exit
+--     status along with the selected item's text instead of the button's index
+--     or the exit code along with the item's index. The default value is
+--     `false`.
+--   * `width`: The pixel width of the dialog.
+--   * `height`: The pixel height of the dialog.
+--   * `float`: Show the dialog on top of all desktop windows. The default value
+--     is `false`.
+--   * `timeout`: The number of seconds the dialog waits for the user to select
+--     a button before timing out. Dialogs do not time out by default.
+-- @return selected button or exit code, selected item or list of selected items
+-- @usage ui.dialogs.filteredlist{title = 'Title', columns = {'Foo', 'Bar'},
+--   items = {'a', 'b', 'c', 'd'}}
+function filteredlist(options) end
diff --git a/core/file_io.lua b/core/file_io.lua
index ce3bf8ec..09533196 100644
--- a/core/file_io.lua
+++ b/core/file_io.lua
@@ -91,22 +91,22 @@ io.boms = {
 io.encodings = {'UTF-8', 'ASCII', 'ISO-8859-1', 'MacRoman'}
 
 ---
--- Opens *filenames*, a "\n" delimited string of filenames, or user-selected
--- files.
+-- Opens *filenames*, a string filename, table of filenames, or user-selected
+-- filenames.
 -- Emits a `FILE_OPENED` event.
--- @param filenames Optional string list filenames to open. If `nil`, the user
---   is prompted with a fileselect dialog.
+-- @param filenames Optional string filename or table of filenames to open. If
+--   `nil`, the user is prompted with a fileselect dialog.
 -- @see _G.events
 -- @name open_file
 function io.open_file(filenames)
-  filenames = filenames or
-              ui.dialog('fileselect',
-                        '--title', _L['Open'],
-                        '--select-multiple',
-                        '--with-directory',
-                        (buffer.filename or ''):match('^.+[/\\]') or '')
-  for filename in filenames:gmatch('[^\n]+') do
-    filename = filename:gsub('^file://', '')
+  if type(filenames) == 'string' then filenames = {filenames} end
+  filenames = filenames or ui.dialogs.fileselect{
+    title = _L['Open'], select_multiple = true,
+    with_directory = (buffer.filename or ''):match('^.+[/\\]')
+  }
+  if not filenames then return end
+  for i = 1, #filenames do
+    local filename = filenames[i]:gsub('^file://', '')
     if WIN32 then filename = filename:gsub('/', '\\') end
     for i, buffer in ipairs(_BUFFERS) do
       if filename == buffer.filename then view:goto_buffer(i) return end
@@ -235,14 +235,12 @@ end
 --   user is prompted for one.
 -- @name save_file_as
 function io.save_file_as(filename)
-  local dir = (buffer.filename or ''):match('^.+[/\\]') or ''
-  local name = (buffer.filename or ''):match('[^/\\]+$') or ''
-  filename = filename or ui.dialog('filesave',
-                                   '--title', _L['Save'],
-                                   '--with-directory', dir,
-                                   '--with-file', name:iconv('UTF-8', _CHARSET),
-                                   '--no-newline')
-  if filename == '' then return end
+  local dir, name = (buffer.filename or ''):match('^(.-[/\\]?)([^/\\]*)$')
+  filename = filename or ui.dialogs.filesave{
+    title = _L['Save'], with_directory = dir,
+    with_file = name:iconv('UTF-8', _CHARSET)
+  }
+  if not filename then return end
   buffer.filename = filename
   io.save_file()
   events.emit(events.FILE_SAVED_AS, filename)
@@ -268,15 +266,13 @@ end
 -- @name close_buffer
 function io.close_buffer()
   local filename = buffer.filename or buffer._type or _L['Untitled']
-  if buffer.dirty and ui.dialog('msgbox',
-                                '--title', _L['Close without saving?'],
-                                '--text', _L['There are unsaved changes in'],
-                                '--informative-text',
-                                filename:iconv('UTF-8', _CHARSET),
-                                '--icon', 'gtk-dialog-question',
-                                '--button1', _L['_Cancel'],
-                                '--button2', _L['Close _without saving'],
-                                '--no-newline') ~= '2' then
+  if buffer.dirty and ui.dialogs.msgbox{
+       title = _L['Close without saving?'],
+       text = _L['There are unsaved changes in'],
+       informative_text = filename:iconv('UTF-8', _CHARSET),
+       icon = 'gtk-dialog-question', button1 = _L['_Cancel'],
+       button2 = _L['Close _without saving']
+     } ~= 2 then
     return nil -- returning false can cause unwanted key command propagation
   end
   buffer:delete()
@@ -306,19 +302,15 @@ local function update_modified_file()
   if not mod_time or not buffer.mod_time then return end
   if buffer.mod_time < mod_time then
     buffer.mod_time = mod_time
-    if ui.dialog('yesno-msgbox',
-                 '--title', _L['Reload?'],
-                 '--text', _L['Reload modified file?'],
-                 '--informative-text',
-                 ('"%s"\n%s'):format(buffer.filename:iconv('UTF-8', _CHARSET),
-                                     _L['has been modified. Reload it?']),
-                 '--icon', 'gtk-dialog-question',
-                 '--button1', _L['_Yes'],
-                 '--button2', _L['_No'],
-                 '--no-cancel',
-                 '--no-newline') == '1' then
-      io.reload_file()
-    end
+    local msg = string.format('"%s"\n%s',
+                              buffer.filename:iconv('UTF-8', _CHARSET),
+                              _L['has been modified. Reload it?'])
+    local button = ui.dialogs.msgbox{
+      title = _L['Reload?'], text = _L['Reload modified file?'],
+      informative_text = msg, icon = 'gtk-dialog-question',
+      button1 = _L['_Yes'], button2 = _L['_No']
+    }
+    if button == 1 then io.reload_file() end
   end
 end
 events_connect(events.BUFFER_AFTER_SWITCH, update_modified_file)
@@ -342,14 +334,16 @@ function io.open_recent_file()
   for _, filename in ipairs(io.recent_files) do
     utf8_filenames[#utf8_filenames + 1] = filename:iconv('UTF-8', _CHARSET)
   end
-  local i = ui.filteredlist(_L['Open'], _L['File'], utf8_filenames, true,
-                            CURSES and {'--width', ui.size[1] - 2} or '')
-  if i then io.open_file(io.recent_files[i + 1]) end
+  local button, i = ui.dialogs.filteredlist{
+    title = _L['Open'], columns = _L['File'], items = utf8_filenames,
+    width = CURSES and ui.size[1] - 2 or nil
+  }
+  if button == 1 and i then io.open_file(io.recent_files[i]) end
 end
 
 ---
--- Quickly open files from *paths*, a "\n" delimited string of directory paths,
--- using a filtered list dialog.
+-- Quickly open files from *paths*, a string directory path or table of
+-- directory paths, using a filtered list dialog.
 -- Files shown in the dialog do not match any pattern in string or table
 -- *filter*, and, unless *exclude_FILTER* is `true`, `lfs.FILTER` as well. A
 -- filter table contains Lua patterns that match filenames to exclude, with
@@ -358,13 +352,14 @@ end
 -- pattern that follows. Use a table of raw file extensions assigned to an
 -- `extensions` key for fast filtering by extension. The number of files in the
 -- list is capped at `SNAPOPEN_MAX`.
--- @param paths String list of directory paths to search.
+-- @param paths String directory path or table of directory paths to search.
 -- @param filter Optional filter for files and folders to exclude.
 -- @param exclude_FILTER Optional flag indicating whether or not to exclude the
 --   default filter `lfs.FILTER` in the search. If `false`, adds `lfs.FILTER` to
 --   *filter*.
 --   The default value is `false` to include the default filter.
--- @param ... Optional additional parameters to pass to `ui.dialog()`.
+-- @param opts Optional additional options to pass to
+--   `ui.dialogs.filteredlist()`.
 -- @usage io.snapopen(buffer.filename:match('^.+/')) -- list all files in the
 --   current file's directory, subject to the default filter
 -- @usage io.snapopen('/project', '!%.lua$') -- list all Lua files in a project
@@ -374,27 +369,32 @@ end
 -- @see lfs.FILTER
 -- @see SNAPOPEN_MAX
 -- @name snapopen
-function io.snapopen(paths, filter, exclude_FILTER, ...)
+function io.snapopen(paths, filter, exclude_FILTER, opts)
+  if type(paths) == 'string' then paths = {paths} end
   local utf8_list = {}
-  for path in paths:gmatch('[^\n]+') do
-    lfs.dir_foreach(path, function(file)
+  for i = 1, #paths do
+    lfs.dir_foreach(paths[i], function(file)
       if #utf8_list >= io.SNAPOPEN_MAX then return false end
       file = file:gsub('^%.[/\\]', ''):iconv('UTF-8', _CHARSET)
       utf8_list[#utf8_list + 1] = file
     end, filter, exclude_FILTER)
   end
   if #utf8_list >= io.SNAPOPEN_MAX then
-    ui.dialog('ok-msgbox',
-              '--title', _L['File Limit Exceeded'],
-              '--text',
-              string.format('%d %s %d', io.SNAPOPEN_MAX,
-                            _L['files or more were found. Showing the first'],
-                            io.SNAPOPEN_MAX),
-              '--icon', 'gtk-dialog-info',
-              '--button1', _L['_OK'])
+    local msg = string.format('%d %s %d', io.SNAPOPEN_MAX,
+                              _L['files or more were found. Showing the first'],
+                              io.SNAPOPEN_MAX)
+    ui.dialogs.msgbox{
+      title = _L['File Limit Exceeded'], text = msg, icon = 'gtk-dialog-info'
+    }
   end
-  local width = CURSES and {'--width', ui.size[1] - 2} or ''
-  local files = ui.filteredlist(_L['Open'], _L['File'], utf8_list, false,
-                                '--select-multiple', width, ...) or ''
-  io.open_file(files:iconv(_CHARSET, 'UTF-8'))
+  local options = {
+    title = _L['Open'], columns = _L['File'], items = utf8_list,
+    button1 = _L['_OK'], button2 = _L['_Cancel'], select_multiple = true,
+    string_output = true, width = CURSES and ui.size[1] - 2 or nil
+  }
+  if opts then for k, v in pairs(opts) do options[k] = v end end
+  local button, files = ui.dialogs.filteredlist(options)
+  if button ~= _L['_OK'] or not files then return end
+  for i = 1, #files do files[i] = files[i]:iconv(_CHARSET, 'UTF-8') end
+  io.open_file(files)
 end
diff --git a/core/ui.lua b/core/ui.lua
index 8149b9d7..f1ed2e30 100644
--- a/core/ui.lua
+++ b/core/ui.lua
@@ -70,43 +70,49 @@ function ui._print(buffer_type, ...) pcall(_print, buffer_type, ...) end
 -- @name print
 function ui.print(...) ui._print(_L['[Message Buffer]'], ...) end
 
----
--- Convenience function for `ui.dialog('filteredlist', ...)` with "Ok" and
--- "Cancel" buttons that returns the text or index of the selection depending on
--- the boolean value of *int_return*.
--- *title* is the title of the dialog, *columns* is a list of column names, and
--- *items* is a list of items to show.
--- @param title The title for the filtered list dialog.
--- @param columns A column name or list of column names.
--- @param items An item or list of items.
--- @param int_return Optional flag indicating whether to return the integer
---   index of the selected item in the filtered list or the string selected
---   item. A `true` value is not compatible with the `'--select-multiple'`
---   option. The default value is `false`.
--- @param ... Optional additional parameters to pass to `ui.dialog()`.
--- @return Either a string or integer on success; `nil` otherwise. In strings,
---   multiple items are separated by newlines.
--- @usage ui.filteredlist('Title', 'Foo', {'Bar', 'Baz'})
--- @usage ui.filteredlist('Title', {'Foo', 'Bar'}, {'a', 'b', 'c', 'd'}, false,
---                        '--output-column', '2')
--- @see dialog
--- @name filteredlist
-function ui.filteredlist(title, columns, items, int_return, ...)
-  local out = ui.dialog('filteredlist',
-                        '--title', title,
-                        '--button1', _L['_OK'],
-                        '--button2', _L['_Cancel'],
-                        '--no-newline',
-                        int_return and '' or '--string-output',
-                        '--columns', columns,
-                        '--items', items,
-                        ...)
-  local patt = int_return and '^(%-?%d+)\n(%d+)$' or '^([^\n]+)\n(.+)$'
-  local response, value = out:match(patt)
-  if response == (int_return and '1' or _L['_OK']) then
-    return not int_return and value or tonumber(value)
+-- Documentation is in core/.ui.dialogs.luadoc.
+ui.dialogs = setmetatable({}, {__index = function(t, k)
+  -- Wrapper for `ui.dialog(k)`, transforming the given table of arguments into
+  -- a set of command line arguments and transforming the resulting standard
+  -- output into Lua objects.
+  -- @param options Table of key-value command line options for gtdialog.
+  -- @return Lua objects depending on the dialog kind
+  return function(options)
+    if not options.button1 then options.button1 = _L['_OK'] end
+    if options.select then options.select = options.select - 1 end
+    -- Transform key-value pairs into command line arguments.
+    local args = {}
+    for option, value in pairs(options) do
+      if value then
+        args[#args + 1] = '--'..option:gsub('_', '-')
+        if value ~= true then args[#args + 1] = value end
+      end
+    end
+    -- Call gtdialog, stripping any trailing newline in the standard output.
+    local result = ui.dialog(k:gsub('_', '-'), table.unpack(args))
+    result = result:match('^(.-)\n?$')
+    -- Depending on the dialog type, transform the result into Lua objects.
+    if k == 'fileselect' or k == 'filesave' then
+      if result == '' then return nil end
+      if k == 'filesave' or not options.select_multiple then return result end
+      local files = {}
+      for file in result:gmatch('[^\n]+') do files[#files + 1] = file end
+      return files
+    elseif k == 'filteredlist' then
+      local button, value = result:match('^([^\n]+)\n?(.*)$')
+      if not options.string_output then button = tonumber(button) end
+      local items = {}
+      for item in value:gmatch('[^\n]+') do
+        items[#items + 1] = options.string_output and item or tonumber(item) + 1
+      end
+      return button, options.select_multiple and items or items[1]
+    elseif not options.string_output then
+      local i, value = result:match('^(%-?%d+)\n?(.*)$')
+      return tonumber(i), k ~= 'dropdown' and value or tonumber(value) + 1
+    end
+    return result:match('([^\n]+)\n(.*)$')
   end
-end
+end})
 
 ---
 -- Prompts the user to select a buffer to switch to.
@@ -120,9 +126,11 @@ function ui.switch_buffer()
     items[#items + 1] = (buffer.dirty and '*' or '')..basename
     items[#items + 1] = filename
   end
-  local i = ui.filteredlist(_L['Switch Buffers'], columns, items, true,
-                            CURSES and {'--width', ui.size[1] - 2} or '--')
-  if i then view:goto_buffer(i + 1) end
+  local button, i = ui.dialogs.filteredlist{
+    title = _L['Switch Buffers'], columns = columns, items = items,
+    width = CURSES and ui.size[1] - 2 or nil
+  }
+  if button == 1 and i then view:goto_buffer(i) end
 end
 
 ---
@@ -357,15 +365,12 @@ events_connect(events.QUIT, function()
       list[#list + 1] = filename:iconv('UTF-8', _CHARSET)
     end
   end
-  return #list < 1 or ui.dialog('msgbox',
-                                '--title', _L['Quit without saving?'],
-                                '--text',
-                                _L['The following buffers are unsaved:'],
-                                '--informative-text', table.concat(list, '\n'),
-                                '--icon', 'gtk-dialog-question',
-                                '--button1', _L['_Cancel'],
-                                '--button2', _L['Quit _without saving'],
-                                '--no-newline') == '2'
+  return #list < 1 or ui.dialogs.msgbox{
+    title = _L['Quit without saving?'],
+    text = _L['The following buffers are unsaved:'],
+    informative_text = table.concat(list, '\n'), icon = 'gtk-dialog-question',
+    button1 = _L['_Cancel'], button2 = _L['Quit _without saving']
+  } == 2
 end)
 
 events_connect(events.ERROR, ui.print)
@@ -388,14 +393,16 @@ local size
 The functions below are Lua C functions.
 
 ---
--- Displays a [gtdialog][] of kind *kind* with the given string arguments to
--- pass to the dialog and returns a formatted string of the dialog's output.
+-- Low-level function for prompting the user with a [gtdialog][]s of kind *kind*
+-- with the given string and table arguments, returning a formatted string of
+-- the dialog's output.
+-- You probably want to use the higher-level functions in the [`ui.dialogs`][]
+-- module.
 -- Table arguments containing strings are allowed and expanded in place. This is
 -- useful for filtered list dialogs with many items.
--- For more information on gtdialog, see [http://foicica.com/gtdialog][].
 --
 -- [gtdialog]: http://foicica.com/gtdialog/02_Usage.html
--- [http://foicica.com/gtdialog]: http://foicica.com/gtdialog
+-- [`ui.dialogs`]: ui.dialogs.html
 -- @param kind The kind of gtdialog.
 -- @param ... Parameters to the gtdialog.
 -- @return string gtdialog result.