By default, it works like this:

SHIFT+1 opens Window00
SHIFT+2 opens Window01
SHIFT+3 opens Window02
SHIFT+4 opens Window03
SHIFT+5 opens Window04
SHIFT+6 opens Window05
SHIFT+7 opens Window06
SHIFT+8 opens Window07
SHIFT+9 opens Window08

This is because panel Window00 is the first one, making it window #1. Window08 is the ninth, therefore it is window #9.

You can change in Settings > Controls > Buttons / Keys

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