There is a behavior on windows where an application will sound a bell and flash when an action failed by a user.
Example: saving a file in kate, a popup dialogue will appear confirming if the user would like to save. if the user clicks somewhere in the text editor, the popup dialogue or window should flash and the system bell should sound to alert the user that they did not interact with the pop-up dialogue.
This would be useful for people that use screen zoom or have the popup dialogue hidden behind another window.
Can confirm that, in Plasma 6.3.4, this is not how modal dialogs work.
I opened Kate, created a new document, wrote some text, hit Alt+F4, heard the “Are you sure youo want to quit?” dialog pop up.
Attempting to interact with the main Kate window while that dialog is open, won’t work. That’s a good thing.
I do think adding at least an audible bell would be useful in case the user doesn’t see whatever modal dialog is interrupting the window (happens to me quite often). I’m not sure how a decorator flash would look though. It would be nice to know which window is interrupting things.