Bug fix: Failure when trying to switch session tabs while previous switch did not complete yet

Source commit: 6c0ba273dabd86e9e8c5fee52de4aa13f6e55164

source/forms/CustomScpExplorer.cpp

@@ -7169,6 +7169,7 @@ bool __fastcall TCustomScpExplorerForm::SessionTabSwitched()
 //---------------------------------------------------------------------------
 void __fastcall TCustomScpExplorerForm::SessionsPageControlChange(TObject * /*Sender*/)
 {
+  TWindowLock Lock(this);
   SessionTabSwitched();
 }
 //---------------------------------------------------------------------------