Add wxTreeCtrl::{Clear,Set}FocusedItem().

Allow changing just the currently focused (not selected) item and also
removing the focus completely.

Closes #11599.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64196 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/treectlg.cpp

@@ -1953,6 +1953,20 @@ void wxGenericTreeCtrl::Unselect()
     }
 }
 
+void wxGenericTreeCtrl::ClearFocusedItem()
+{
+    wxTreeItemId item = GetFocusedItem();
+    if ( item.IsOk() )
+        SelectItem(item, false);
+}
+
+void wxGenericTreeCtrl::SetFocusedItem(const wxTreeItemId& item)
+{
+    wxCHECK_RET( item.IsOk(), wxT("invalid tree item") );
+
+    SelectItem(item, true);
+}
+
 void wxGenericTreeCtrl::UnselectAllChildren(wxGenericTreeItem *item)
 {
     if (item->IsSelected())