"Grab Region", what's the region?

[SaT_Admin]

Or should I make sure that all the pixels of the button are within that region?

This. Its not exact, but you want to cover as much as the button as you can.

How should I approach this, and may I also ask what SaT uses these regions for?

SaT uses these regions to determine when you've clicked on the fold/call/bet buttons on a table. If a click is detected within this rectangle, then SaT thinks that you've clicked on the button that is associated with that rectangle.

This is used in two places:

1. Tables in the grid will be sent back to the stack when you click on the Fold button.
2. Tables in the stack will be sent to the grid when you click on either the Call or Bet buttons, when using Tile Setting = After Entering Pot

To enable this detection, there is the option for "Left mouse click detection" in Advanced Options