PopupMenu is not a FlowChartX property, but Delphi adds it automatically and probably tries to implement it by handling mouse events sent to the FlowChartX window. Since FlowChartX does some complex mouse handling, Delphi cannot detect the mouse operations and won't display the menu. You will need to handle one of the Clicked events raised by the control, e.g. BoxClicked, TableClicked, DocClicked and show the menu from the event handler.

Stoyan