Don't recreate the native control in wxOSX wxDataViewCtrl dtor.

Don't call ClearColumns() which recreates the control in order to remove its
columns in wxOSX/Cocoa, just clean up the internal data, the control, and its
columns, will soon be deleted anyhow.

Closes #16210.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76639 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Don't leak wxDataViewCtrl column objects in wxOSX/Cocoa.

NSOutlineView addTableColumn method takes ownership of the column passed to
it, so we must release it ourselves to avoid leaking it.

Closes #16223.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76640 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Fix memory leak when using custom renderers in wxOSX wxDataViewCtrl.

wxDataViewRendererNativeData retains a reference to the cell passed to it, so
the cell must be released after passing it to wxDataViewRendererNativeData to
avoid leaking it.

Closes #16226.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76641 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Don't leak sort descriptors array in wxDataViewCtrl in wxOSX.

wxCocoaOutlineDataSource owns its sortDescriptors field, so it must release it
in its dealloc() (and also initialize it in its init(), no idea how did it
work without this being done before).

Closes #16231.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76642 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Relax checking window visibility in wxGLCanvas::SetCurrent().

It is enough for the window to be shown for SetCurrent() to work, it doesn't
have to be actually visible on screen, and checking for this using
IsShownOnScreen() resulted in false positives.

Closes #16193.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76644 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775