KDE's Open/Save dialogs are widely considered to be the best in the Linux world, but there's far more we can do to make them truly exceptional. Here are some ideas.
##Design goal 1: Optimize view modes for common use cases##
We identify two common use search modes for locating files or directories: 1) based on their filenames or metadata, and 2) based on their content or appearance. For the former, a compact optimized list-style view with columns of additional information is ideal. For the latter, a large-icons-style view with previews is ideal. Implementing this will require the following changes:
[x] Always perfectly size and align column widths so that {nav Detailed View} and {nav Detailed Tree View} are actually usable: D11993
[x] Improve grid spacing so that {nav Short View} with "Icons on Top" is actually usable at medium and large sizes: D12306
[x] Show buttons on the toolbar to allow easily toggling between {nav Short View} and {nav Detailed Tree View}: D12077
[x] Fix previews to apply to all supported file types (fixes https://bugs.kde.org/show_bug.cgi?id=318493): D12389
[] Make Previews only show up for icons (in any view mode) larger then 24px or so, as they are unusable and useless at such small sizes: D12321
[] Turn on previews by default: D12328
[] For {nav Short View}, default to using "Icons on Top" make the default icon size 64px for {nav Short View} only (fixes https://bugs.kde.org/show_bug.cgi?id=86838): D12326
[] Make `KDirOperator` display {nav Detailed Tree View} by default: D12327
##Design goal 2: improve efficiency and safety of overwrite behavior##
(Relevant information: D12346#249638)
[] When a file will be overwritten, handle that in the file dialog itself, rather than closing the dialog and displaying another pop-up window, or making the calling app handle it (Fixes https://bugs.kde.org/show_bug.cgi?id=102972). Some apps already do this right (like Gwenview, as of D12346), but some don't (Kate).
[] Once the above is done, allow the file dialog to trigger overwrite on double click (irrespective of the click setting) without having to additionally click the {nav Save} button afterwards (fixes https://bugs.kde.org/show_bug.cgi?id=267749): D12538
[] When a file is overwritten using the Save dialog, display a notification with an {nav undo} button in it that will undo the overwrite operation and restore the overwritten file
##Generally improve polish and usability##
[] Add column view navigation: D7929
[] When the dialog displays a combobox of file type options, display the string "File type:" instead of "Filter:" D12130
[] Remove the reload button from the toolbar: D12218
[] Move the Filter functionality into KDirOperator itself, allowing clients to use it and visually connecting it with the view, while also matching Dolphin's Filter UI (Fixes https://bugs.kde.org/show_bug.cgi?id=179483)
[] Move the sorting functionality from the {nav Settings} button to a dropdown menu button on the toolbar to expose this otherwise-mostly-hidden functionality: D12337
[] Make the toolbar editable (fixes https://bugs.kde.org/show_bug.cgi?id=137837)
[] Allow drag-and-drop to the KDirOperator part of the dialog, not just to the filename field (fixes https://bugs.kde.org/show_bug.cgi?id=45154)
[] Add an option to the {nav Settings} menu to return focus to the filename field when the user starts to type (fixes https://bugs.kde.org/show_bug.cgi?id=207750)
[] Allow rubber band selection in list-style views (fixes https://bugs.kde.org/show_bug.cgi?id=271399)
[] Move the {nav New Folder} button to the bottom row of buttons to match where it is in the "select a directory" chooser
[] Move the "icon position" submenu into the top-level configuration popup menu (patch incoming)
[] Improve default width of embedded {nav Places} panel
[] Align the {nav Places} panel with the `KDirOperator` view such that the toolbar goes above it, just like Dolphin: D12333
[] Make sure the return/enter keys are almost always bound to the {nav Save} or {nav Open} button (fixes https://bugs.kde.org/show_bug.cgi?id=385189)
[] Improve thumbnail quality (fixes https://bugs.kde.org/show_bug.cgi?id=345578): D12385
[] Don't select filename extension when auto-selecting the filename: D12544
##Add requested features##
[x] Add a Reload item to the context menu: D12215
[] Add a Rename item to the context menu (fixes https://bugs.kde.org/show_bug.cgi?id=189482)
[] Add more sorting options (Fixes https://bugs.kde.org/show_bug.cgi?id=155583)
##Fix bugs##
[x] Always save view settings when canceling or closing the dialog: D12227 and D12240
[] Fix/reduce the scroll speed when icons are very large (fixes https://bugs.kde.org/show_bug.cgi?id=223937; see also the same problem in Dolphin: https://bugs.kde.org/show_bug.cgi?id=386379)
[] Always save view settings when switching from one view mode to another (e.g. from {nav Short View} to {nav Detailed Tree View} and back.
[] Supported File Types list should be sorted alphabetically (fixes https://bugs.kde.org/show_bug.cgi?id=47750)
[] When multi-selection is allowed, ignore any selected folders, and/or disallow folder selection when any files are already selected)(fixes https://bugs.kde.org/show_bug.cgi?id=271400)
[] Fix keyboard navigation with Icons-on-the-side in {nav Short View} (fixes https://bugs.kde.org/show_bug.cgi?id=148635)
[] Make the minimum icon size in KDirOperator respect the global "Small icon size" minimum (fixes https://bugs.kde.org/show_bug.cgi?id=339662)
[] Disable the zoom buttons once the slider reached either end (patch incoming)
[] Set a minimal size for the zoom slider (patch incoming)
[] Fix a bug where after every save the places panel got 1px wider (patch incoming)
[] Perfectly align the name widget to the file view (patch incoming)
[] Show selection markers when the click mode is Single Click (fixes https://bugs.kde.org/show_bug.cgi?id=185793)
[] Make the dialogs open at a reasonable size on humongous 4k screens
[] Fix the flickering when previews are turned on and icons are resized using the slider
[] Fix issue with preview panel showing the wrong file when the cursor passes over another item and leaves the `KDirOperator` viewport without first passing over the background (fixes https://bugs.kde.org/show_bug.cgi?id=247268)
[] Fix location of progress bar that appears when the file list takes a long time to load (Fixes https://bugs.kde.org/show_bug.cgi?id=194017)
[] Fix bug that prevented select-filename-on-click from working with double-click: D12545