[Lazarus] VirtualTreeView, clicking to expand collapse only on works for first column

[Jürgen Hestermann]

In a VirtualTreeView I have icons to expand and collapse
subnodes (the + and - in a square).
When clicking on them with the mouse it only works
when the column with these icons is the first (left) column.
When I change the main column or when I move the first
column to the right (so that it's not the most left one anymore)
clicking on these icons does nothing.

Is this a known bug?