- caret: Use the system color for window background instead of
hard-coded white.
- image: Use hard-coded black for the text drawing since all other
drawings on the image canvas use hard-coded colours too. The default
text colour was barely readable in dark mode.
- joytest: Use wxCYAN_PEN instead of wxBLACK_PEN to ensure the line is
visible both in light and dark colour system mode.
- ownerdrw: Use such background colour that there is good contrast
between text and background both in light and dark colour system mode.
- popup: Use such background colour for the pop up so that there is a
good contrast between text and background both in light and dark
colour system mode.
Closes#23773.