[Lazarus] Anchoring fails on Windows 10

[Jürgen Hestermann]

I have a simple form with 2 components,
a TVirtualDrawTree and a TProgressBar.

The TProgressBar is anchored to the bottom of the form and
the bottom of the TVirtualDrawTree is anchored to the top of the TProgressBar.

This works okay on Windows 7 and 8.1 but not on Windows 10!
When I resize the form by moving down the bottom border or
by making it full size then the position of the TProgressBar
within the form stays where it was
and is not moved to the bottom of the form.

Anybody else having such issues on Windows 10?