With this tool, you can resize the red rectangle thing, easily.

Downloads (download both files!):
redsize.pd
redsize_abs.pd

INSTRUCTIONS:

1. It is an abstraction, so you put it in your abstractions folder (Pd path). In fact, there are two files: redsize.pd and redsize_abs.pd.

2. Activate graph on parent, (if you haven't done it yet).

3. Call redsize into your subpatch, abstraction, or whatever, by typing redsize into an object box.

4. You are going to see this:
   

5. Open it, and there you´ll find all necessary controls and simple instructions. Basically, you'll control the red rectangle from a small window.

Notice that it's a variation on the work done by @sensn who generously shared it 3 months ago here: http://forum.pdpatchrepo.info/topic/8590/graph-on-parent-box/
Also, his recent comments have made me correct a few bugs! Thank you sensn.

Hello,

here is another approach at resizing the GOP-rectangle. While "redsize_abs" shared and well documented by Landon is quite vanilla, the one I'm going to share uses some externals from iem and cyclone. So, this version is for pd-extended.

Inside the "redmouse" folder you will find "redmouse_abs.pd" and "redmouse_Main.pd". Open "redmouse_Main" and let me know what you think.
Resizing will work in edit and runmode. However the abstraction will put the Main patch into editmode automatically. If you don't like it (it's somehow not precize because you'll tend to move objects accidently) just delete the "editmode 1" message in the abstraction. I added it for visual feedback (selection-rectangle) only.
To get the pd-coordinates i had a look at hcs/mouseregion. It mainly makes use of iem/recievecanvas.

Maybe we should combine both methods for the ultimate redrectangle-abstraction?

I have a dream of a dynamic-patching toolbox-abstraction that makes creating Gui-elements with custom properties faster and easier for the user. I wonder what other people use...

redmouse.zip

Thanks for sharing that tool, sensn. It works nicely.

I wonder if one could mix the best of both approaches. Honestly, I find your approach more difficult. My approach (based on your original approach LOL!) seems more user friendly to me, I mean, more straightforward. I explained (only some of!) my problems at: http://forum.pdpatchrepo.info/topic/8590/graph-on-parent-box/

The other thing I notice is that redmouse is, obviously, very quick. But there's no fine adjustment in it.

So I see some some limitations in the solutions we have so far. That's why I wonder if one could mix the best of both approaches.

Nevertheless, we have created useful rectangle managers and we should be glad for that!