I agree with this. While it would certainly useful to file specific issues for each instance of message that needs improving, I think a set of general UI guidelines would be great to have if they could be developed and agreed on. I think this is great start. It's not about dumbing down, it's about generalizing and clarifying. It is analogous to coding principles of say, naming functions or classes for the WHAT and not the HOW; the purpose not the implementation detail.

I would add to this another:

If you don't have text for a tooltip that actually adds additional information, don't put it in. Don't just rephrase it in non-abbreviated form unless the abbreviated form is actually ambiguous.

For example, on the Akonadi Server Configuration panel, there is a checkbox for "Use internal MySQL server". Try clicking the ? icon and clicking on this I control, and you get "Choose whether Akonadi should Use and internal or external MySQL server."

I'd like to add some references to our recently updated HIG.

Tooltips: http://techbase.kde.org/Projects/Usability/HIG/Tooltip
Notifications: http://techbase.kde.org/Projects/Usabil ... ifications
Wording: http://techbase.kde.org/Projects/Usability/HIG/Wording

and Text in general: http://techbase.kde.org/Projects/Usability/HIG#Text

I second Heiko here: Guidelines do exist. Please feel free to have a look at them and make specific suggestions on how they can be improved. Suggestions for new guidelines are welcome, too!