Just started using Construct some minutes ago. Whilst I think its interesting how you solved the rotation of sprites (the small gizmo in the middle) I think if I would use Construct often it would make me a bit mad if I switch often between other applications like photoshop (e.g. for editing my sprites) where you can rotate by keeping the mouse button pressed outside the bounding box of a 'sprite' or transform object. For a good workflow you should include the regular rotation.
Actually also a fixed scaling would be nice. Mmh after writing the first paragraph I played around more and I see why you made your gizmo like it is (clicking background etc), but if you are aiming at professional developers I think you should somehow revisit the gizmo, maybe a hotkey for using a photoshop like gizmo or something.
I am using r87.