If you want to do that in the editor you can select the objects, right click on that, and select wrap selection (shortcut key is return I think).
If you want to do it when running the game you can do this:
Global number scale=0.5
Global number centerx=320
Global number centery=240
Start of layout
— sprite: set x to (self.x-centerx)*scale +centerx
— sprite: set y to (self.y-centery)*scale +centery
— sprite: set width to self.width*scale
— sprite: set height to self.height*scale
That will scale around any center instead of just the object centers.
To have actual resize handles at runtime is a bit more involved. There is a resize handle example you should be able to find with the search I think.
This code doesn't scale object like in the gif that i posted above. I know about wrap selection, but that can't help me, because i want to resize sprites inside the game, during runtime.
Your code resizes sprites like this:
EDIT: I had pin behavior enabled, so resizing was wrong in this gif. When i turn if off during resizing it works perfect. Thanks!