Bug when TBCButton (bgracontrol package) is combined with TLazVirtualStringTree

[szlbz]

Only one of these two controls can run normally, but when both controls are used together, if the FontEx.style of TBCButton is set to empty, it will crash when running on Linux. When running on the terminal, the following error message can be seen:

Gtk-Message: 07:44:34.383: Failed to load module "ukuireload-gtk-module"
(wsms-x86_64-linux:40963): Pango-CRITICAL **: 07:44:36.819: pango_layout_get_text: assertion 'PANGO_IS_LAYOUT (layout)' failed
(wsms-x86_64-linux:40963): Pango-CRITICAL **: 07:44:36.820: pango_layout_get_pixel_extents: assertion 'PANGO_IS_LAYOUT (layout)' failed
(wsms-x86_64-linux:40963): Pango-CRITICAL **: 07:44:36.820: pango_layout_get_text: assertion 'PANGO_IS_LAYOUT (layout)' failed

lazarus 4.2
fpc 3.3.1
ubuntu 20.4 gtk2

demo.zip

Please help to handle it, thank！