+ Thaw();
+}
+
+void wxTreeCtrlBase::CollapseAll()
+{
+ if ( IsEmpty() )
+ return;
+
+ CollapseAllChildren(GetRootItem());
+}
+
+void wxTreeCtrlBase::CollapseAllChildren(const wxTreeItemId& item)
+{
+ Freeze();
+ // first (recursively) collapse all the children
+ wxTreeItemIdValue cookie;
+ for ( wxTreeItemId idCurr = GetFirstChild(item, cookie);
+ idCurr.IsOk();
+ idCurr = GetNextChild(item, cookie) )
+ {
+ CollapseAllChildren(idCurr);
+ }
+
+ // then collapse this element too
+ Collapse(item);
+ Thaw();
+}
+
+bool wxTreeCtrlBase::IsEmpty() const
+{
+ return !GetRootItem().IsOk();