Assertion on closing codeblocks due to wxWidgets 3.3

[christo]

There is a regression in wxWidgets causing assertion window on closing codeblocks if the project tree is expanded and is big.

Code

../src/generic/treectlg.cpp(1539): assert "IsVisible(item)" failed in GetNextVisible(): this item itself should be visible

I've reported it to wxWidgets project and fix is identified. https://github.com/wxWidgets/wxWidgets/issues/26839

[Miguel Gimenez]

There is a similar issue, see wxTreeCtrl::GetFirstVisibleItem() returns invisible item on MSW if the tree is hidden. I added an item visibility check to avoid an assertion when the project tree was hidden on project loading.