I havent check it out on the new Win 7 yet but
had similar problems with it on both xp and Vista.
Like you I too use Construct to quickly mock-up ideas
rather then having to code in Visual Studio and yes the
combo box has been a disappointment...I would keep
checking it with each new version of construct and
oh-well. I do alot of non-game constructing and just
work around combobox issue with listbox and editbox
and sometimes make it go invisible (listbox) kinda like
a context menu...using a text object as tigger but
this can get kinda complex so like you I do at times find
myself back in C++ or VB humping code but I would hate
to have them remove what eventually well be a very
useful object. I see construct as so much more then
a game-maker and my greatest fear is that it well slip
into a specialty rut. If the developers think "oh its
a game making app so lets take all these things out"
then I believe a great idea well have just become
a neat idea and what was AMAZING well fall to the
status of pretty cool. So keep the combo box.