[Lazarus] Lazarus Release Candidate 1 of 1.4. Message cannot be stopped

[Jürgen Hestermann]

I use Lazarus V1.4RC1 on Win7 and today I had a strange situation:

I started to build and run an application with F9.
But my machine was quite slow so nothing (visible)
happened for many seconds.
It could be that I then hit F9 again.
After a while I got an error message saying:

Stop current debugging and rebuild project?

But this message could not be stopped.
Clicking on Yes or No had no effect.
The message stayed (or reappeared quickly).
I had to exit from Lazarus and restart  it to be able to continue.

Maybe someone can fix this easily.