Hi Cornan, nice to see you haven't lost your indignation about these issues that beset us all!
Every time Expanded View starts to get me down, which is often, I recite Hannes' signature quote several times like a mantra:
Furthermore I think PersonalBrain is unique
after that, things seem to improve and are placed in perspective...
Seriously, what helps me in this situation is to right-click (or r-click-drag), not left-click any thought in the plex; then it won't explode. Alternatively, if you left-click it unthinkingly, make sure you drag it slightly before releasing the left mouse button. Dragging also prevents activation.
In addition, if your plex should suddenly become flooded, why not try my idea of pinning an orphan thought named Active to the pin bar. In each Expanded View, click it on the pin bar to activate it and add it to the current plex. Save the plex with Active in the view but it could even be offscreen out of the way. Now, when the plex gets flooded, click Active on the pin bar and then the Collapse tab on the thought that exploded will reappear. Click it and it will collapse. (Yeah, I know it's another workaround for the fact that the active thought has no Collapse tab, but it works.)
Some more suggestions for taming Expanded View are in these 2 threads:
Hope they help.