Why would you want to increase or decrease the size of the border padding for any window you open? I have no idea but here is the regedit tweak you need to do it:
- Open Regedit
- Navigate here: HKEY_CURRENT_USER\Control Panel\Desktop\WindowMetrics
- Right click on PaddedBorderWidth and click Modify
- You will see this;
You can set the border between 0 (no border) and 300 (large border). Personally I have no idea why you would want a border of 300, maybe you could set it on you friends computers to annoy them! You just need to reboot your machine and you will see that you have a new border size.