Being a game developer both professionally and during my time off there are some things that I would like to see implemented in Construct. This is by no means a whine thread as I find Construct superior to all the other game making tools out there (MMF and Unity).
MMF had some pretty sweet features that I'd like to see in Construct. The ability to use LUA for your projects as well as the debug feature. I won't go much in depth about the LUA feature as I think it is pretty self explanatory what it does but sometimes I find myself a bit limited using the "click-scripting". It might be a case of me just not knowing how to use construct that well yet but I would like see a support for LUA as it is a widely used scripting language that is very easy to get into.
The debug feature in MMF was something that I really enjoyed. Instead of having to use text boxes to print the values of variables you could just use the debug box to see the values of all the variables and loops running in real time. This would be very useful, especially for arrays as they are very hard to keep track of in your head. :)
3D support. As much as I love sprites sometimes I find myself wishing I could use 3D models. Mostly for background stuff. I realize that when it comes to models Construct could never compete with unity but the ability to use models from time to time would be pretty sweet.