these are the things I think would be useful additions to construct,
first ability to choose initial direction for bullet behavior, It should be simple to add from what I understand, this would be useful when you are trying to add bullet behavior to sprites in which rotation of sprite matters, say bullet looks like bullet no matter how you rotate it, but when used on say monster that you want fly towards player [from right side of the screen], you might end up with upside down monster if you use set angle or rotate on sprite. this can be fixed by adjusting sprite so that when rotated it looks right or some other fixes, but it would be useful to have this ability built in behavior.
Second is minimap of layout, just like in RTS games
I had to work on very big layout, and zooming out and then scrolling is pain in the ass. Minimap would be helpful, this is probably harder to make, maybe it can be added in future versions.
oh and the ability to create our own subfolders in new events folder in construct 0.99, useful for managing larger projects I think. subfolders in other stuff would also help, like in object window, you could then group sprites together or mission 1 resources together etc.