I think I understand what the OP is getting at.
For example, if you move to the corner in photoshop, it zooms relative.
Quick side-by-side comparison of Photoshop Zoom behaviour and Construct 2 editor canvas.
[TUBE]http://www.youtube.com/watch?v=Fw_WEbSVDjE[/TUBE]
no-so-ninja-edit : forgot TUBE BB tags..