Search for: KB10922 - C++Builder gives a const compiling error on Legend.OnLayerSelect event. In C++Builder XE6, compiling event code like void __fastcall TfrmGUI_RGIS::LegendLayerSelect(const TObject *_sender, const TGIS_LayerAbstract *_layer) { ShowMessage(_layer->Name); } causes a compiling error. The solution is to use a casting (a canonical way): ShowMessage(const_cast<TGIS_LayerAbstract*>(_layer)->Name); Or use a non-canonical way, which surprisingly also works: ShowMessage(((TGIS_LayerAbstract *)_layer)->Name); While this issue was found on XE6, it is probably common for all non CLANG based compilers. Created: August 01, 2016, Modified: August 01, 2016