gtk2, qt5: ApplicationProperties.OnActivate/OnDeactivate fired 3 times

Original Reporter info from Mantis: Alextp2

• Reporter name: CudaText man_

Description:

Demo shows that both events are fired 3 times, see listbox log, on clicking app, then desktop, then app.
https://github.com/Alexey-T/FreePascal-tests/tree/master/Application%20OnActivate

Mantis conversion info:

• Mantis ID: 37868
• OS: ubuntu 20
• Version: 2.1 (SVN)