Yes I mean there is a misalignment when the TIB_LookupCombo drops down.

In Win 10 the two monitors are "extended". The 1st has index 0 in screen.monitors[index] and is on my right.. The 2nd has index 1 and is on my left.

I was looking in IB_GRID.PAS today but gave up too early. I found SetWindowPos(.. ,LeftPos, ...). My problem should be in the calculation of LeftPos which occurs in a case statement on FPopupAlignment just above this call. In the cases there is no case for puLeft... Oh, I see it is the default case, above the case statement. So I put IB_Grid in the debugger and stepped through the code. It works as expected and I do not see the problem I had.The TIB_LookupCombo (LC)  with DropDownAlign = daaLeft is OK. (It seems the property PopupAlignment is the same as property DropDownAlign for LC).