Version:            (using KDE KDE 3.5.6)
Installed from:    Ubuntu Packages
OS:                Linux

In various KDE programs' configure dialogs (such as "Settings->Configure Konqueror..." in Konqi), there are "Defaults" buttons which revert the available settings to factory presets.

However, there is no way for the user to know what differs between his current settings and the defaults (i.e. what the button will actually do) unless he presses the button. If he didn't like the defaults given, then he has to Cancel the dialog and open it up again to carry on tinkering. Also, in a large dialog with many settings it can be hard to tell the difference between the user's settings and the defaults as he has to look really closely at the window when he presses the button and then cancel out and go back in the dialog and repeat.

It would be nice if there was a preview feature for the Defaults button which would temporarily visually alter the settings in the dialog if triggered. The options that differed between the user's current settings and the defaults might also get highlighted in some color (e.g. color of textedits, checkboxes etc.) for easy spotting.

This preview feature could be triggered by hovering the Defaults button with the mouse, but this would present issues in a mouseless (e.g. keyboard driven) environment, and might also be confusing to users who accidentally trigger it. (Unless there is a explanatory text somewhere close to the button stating what happens if you hover it.) Maybe instead a preview checkbox next to the Defaults button? Or something else.

There might also be other use cases within KDE where previewing the behavior of a button would be desired when it's not clear to the user what the button does. Are there any well defined HIG on how to deal with these cases?