Notepad++ plugin with dockingforms crashes; why? (Win 10 64 bit)

[d7_2_laz]

I'm trying to convert, on Windows 10 64bit, a very old (2013) Delphi 7 (32bit, Ansi) Notepad++ plugin to Lazarus 3.6 64 bit, unicode.
And did run into a couple of problems, e.g. a crash "On WM_CREATE", where i don't get a clue where and why (don't know yet how to debug this, so still copying the generated DLL to the belonging Notepad++'s config subfolder).
Notepad++ is from the recent versions (8.7.2 64 bit, portable version). See AccessViolation.jpg.

So i tried a fresh restart using a (hopefully) working example. Found one (meanwhile ancient though) within:
https://forum.lazarus.freepascal.org/index.php/topic,17888.15.html
--> See NPPPluginAndDemo.zip here, within reply #26, from eny.
Result:
Within the plugin demo options, i click "Docking window test", and see a crash, see jpg aattached.

==> Does anybody has any clue how to narrow this down?
Or point to an existing working example with docking forms?

[AlexTP]

Open NP++ plugin in IDE. set 'host app' to NP++. then run the project. it must run NP++ and load your plugin (make sure it loads plugin from dev folder).
Then catch the crash in IDE.

This is what I did when debugging TotalCommander WLX plugin.

[d7_2_laz]

Great hint, thanks Alex!
That should help ... theoretically.  I see a more elaborated error box pointing out a hex address.
Looking in the debug's call stack, i see assembler code ("mov rdx, [rdp+$40]") which is not meaningful itself for me either, as there is no meaningful pre-history i could go back here.
And any breakpoint i set (ie. in the docking form's Create) arrives too late (not reached before the error box appears).

I'd guess that's due to the difference where Notepad++ expects the dll to be (beyond it's plugin subfolder, with a dll name matching the subfolder name), and the place where the DLL will be generated by Lazarus.

Hm. Is there a similar scenario with TotalCommander and WLX plugin?

[d7_2_laz]

News here:
https://forum.lazarus.freepascal.org/index.php/topic,69562.0.html