Weird behaviour of palette

Dear wise women and men:

My script FMfindReplace opens a palette wPalF via menu or short cut. The scipt is started either via the Script Library or by placing it in the Statup folder.

1. I have several documents open and invoke the script via ESC q f
2. It works as intended on document A, Notify reacts and does was it should, all OK
3. I close the palette via the Exit button top right or via the button OK/Done
4. Now I switch to another document B and the palette re-appears! Console log (see Notify hereafter): wPalF.active = true
5. I close the palette and give focus to another application (test editor) and then come back to the document B
6. Now the palette is really gone and for further work with it I invoke it with the short cut... (Console log: wPalF.active = false).

I do not understand why the palette re-appears in step 4. I have not observed such behaviour in any other of my scripts with palettes...

The Notify function is IMHO streight forward:

  case Constants.FA_Note_PostActiveDocChange:
    if (object.ObjectValid()) {                 // change of document
      KLD_F.oCurrentDoc = object;
Console ("wPalF.active = " + wPalF.active);
      if (wPalF.active)  {
        KLD_F.bDocActive = true;
        KLD_F.bBookActive = false;
        wPalF.g07.rbDoc.value = true;
        KLD_F.ButtonReset();
      }
    }

There exist notification constants for which no explanations are in the FDK documentation:

FA_Note_Dialog (84); FA_Note_Alert (85); FA_Note_Palette (86); ... FA_Note_FileOpen (94)
For curiosity I set up notification for FA_Note_Palette  - it did not trigger during my actions.

positive

The palette also re-appears if I open another palette defined by scripts in Statup.