I recently started using KDE 4 and came across some UI design inconveniences. They may seem unimportant for many people but fixing them will improve user experience. Here's a list of them:
Kate:
- native tabs support
- file browser/tree on left side of application window (dock?)
- tabs switching using easy shortcut (Alt+nr)
Hmm, i don't understand the second point, it's already there. Are you using kate or kwrite?
First point, i am not sure if that is necessary if you have the sidebar with all opened files. That's more a question of "what looks nicer" i guess.
Third point, it's already mostly there, just ALT+Arrow-left or right.
Konsole:
- add "new tab" action to context menu as first item
- remove seldom used actions from context menu or move frequently used actions to the begining of the menu (who really often configure and switch profiles or open browser)
- add small X widget on tab corner for easy closing of current tab (like in konqueror)
KMix tray icon:
- remove mute checkbox from popup window invoked be right-clicking, it's already in context menu
- move action (button) for running kmix to context menu
- make slider longer for easier volume control; show volume percentage as tooltip
Plasma:
- Fix layout and size constraints for plasma applets (especially digital clock and system tray). These widgets expand horizontally but shouldn't. Try removing task manager and see what happens.
- applets positioning without going into configuration mode
- task list applet (small icon placed on panel which shows list of all running tasks after clicking) or similar option for current task manager; I'd like to remove task manager to have more space on panel for other applets
The first one already has a bug report and work on that is ongoing. So stay tuned
But for all other items, be sure to check the bug database and if you don't find something, open a new bug, as wishlist item, so nobody will forget it. And you even get the chance to see, if more people would like it, as you can vote for bugs.