For some WM on linux the window decoration is not captured

[sassman]

Describe the bug
On Cinnamon / Linux Mint the window decorations (border buttotns) are not captured.
And when using the parent window id, it captures the border plus some strange pixels (see screenshot).

To Reproduce
Steps to reproduce the behavior:

1. run r-rec
2. or run WINDOWID=<parent window id> t-rec

Expected behavior
The default behaviour should be to capture the window decorations as on Gnome / Ubuntu for example.

Screenshots
this shows the behaviour with using the parent window id:

Desktop (please complete the following information):

• OS: Linux Mint
• Version 20