Version: (using KDE 4.0.82) The current UI is flawed. This is a standard -- show the status, not possibilities. So instead of current what-can-be-done icons, please show: when widget is added (suggestions only) -- a yellow star with "v" mark when it is not -- a gray star _This_ is intuitive, it show the user the status of widgets. Bottom line: do not reinvent the UI, you can make it colorful, but be consistent with standards and KDE.
the star is a way to mark it as a favourite. not particularly rocket science. you're starting to try and look for flaws that aren't causing problems in the real world.
Maybe you can use the "plugins" list on various kde programs. Where the not enabled plugins (here "widgets") are drawn with a grey icon in the list. So to be more intend, on what is added and what is not.
I am not complaining about star. I am complaing that the list is not showing the status what is added what is not added, but what _can_ be added, and what _can_ be removed. So it is contrary to every list you can spot in KDE. Of course you can say, user should re-interpret the minus sign as "added".
yes, it shows what can be added and what can be removed because you can have any number of each widget. because of this difference to every other plugin list in KDE, we don't do it like every other plugin list in KDE. there is a difference in behaviour, therefore a difference in display. =) it also does show the status of what is added by placing a - an the # if it's more than 1. the - sign has a couple of issues (e.g. what exactly are you removing if you have more than one?) and those have bug reports already filed =)