Run attached code.
Click Button..
Content of tree view disappears.
I see output:
Callback for itemnull
Callback for itemnull
..
and so on 20 times.
null is always an argument of callback.
Click Button..
Content of tree view disappears.
I see output:
Callback for itemnull
Callback for itemnull
..
and so on 20 times.
null is always an argument of callback.