Great plugin by the way.
Only one problem and it's sort of a big one at least for me...
If I add the mouse plugin to the project, the combo box stops responding to any sort of mouse activity.
I looked through the forum and didn't see anyone else posting this, which is surprising to me. I would think many people would be running into this.
Ok, I am using Chrome 20.0.1132.57 m, and Construct2 v95.
I did tests stand alone and in my game. The results are the same if using the mouse plugin.
I hope you are interested to fix this and I hope it can be fixed. One suggestion if C2 is stealing your mouse clicks is to add 2 actions: namely "openList" and "close List". That will help even if you can get your clicks because people may sometimes want to handle closing of the list themselves. As for selection, that is a more difficult task, unless C2 will also pass you the coordinates in a mouse condition / event.
Let me know if I can help.