Bigger window resize border

[martinber]

Makes the invisible border around windows a little bigger, so it is easier to resize. I could not find information on why it was only 2 pixels wide (commit). Now the area is 7 pixels wide.

Fixes #937.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• This change requires a documentation update

How Has This Been Tested?

Tested only in Linux, but it should be the same in other platforms

Test Configuration:

• Operating system: Debian GNU/Linux
• Graphics Card: AMD Radeon R7 360. Driver: radeon

Checklist:

• My code follows the code style of this project.
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[alex-w]

7 pixels for border is much IMHO, but for newbies it may be really helpful.