I encountered a following issue. When I click on some link in a GTK based program (for example I like using Pidgin IM), it opens Firefox window, but in the process it breaks grouping in the KDE task manager. I.e. for example I had 4 Firefox windows grouped there (in one). Clicking some link in Pidgin will bring last used Firefox window, but it will also take it out of the group, so there will be 2 groups (1+3) after that. Is there any way to prevent it or it's some kind of GTK/Qt/KDE integration problem?

UPDATE: I figured it really has nothing to do with GTK. I opened a link from Qt based LibreOffice, and the same thing happened. It must have something to do with grouping and the way Firefox is executed probably.