Conditional code when drop down has been activated

Trying to write code so that a shape moves when the drop down menu has been selected.

Basically I want a flag to appear underneath the drop box, but I only want the flag to "drop down" when the combobox drop down list has been selected, ie. when the user presses teh arrow to display the drop down list, the flag will be under the combobox list.

I'm having trouble with this as I can't find anyway for excel to know if the dropdown list specifically has been clicked, it only seems to react if the combobox has been selected or a value in the drop down list clicked.

Please respond with any ideas, or ask for more clarification of problem.

Cheers!