At the moment, Select all (ctrl + A) select all the items on the project.
Could you change it and make it select all the items on the active plate only.
We can keep the select all items on all plates with this shortcut (ctrl + shift + A).
That would be way more convenient.
That would bring it in line with the auto-arrange feature.
Windows
Mac
[Fixed] after @Henlor pointed out I am a dumb a$$. 
I think you meant :
Ctrl + Shift + A = Select All on all plates
Just “A” for arrange all plates is a weird shortcut thought. They should change it as well IMO. Especially since there is a Text tool and because the window focus of this tool is finicky.
I’d blame it on my hand tremors, but, I think this one was just me being dumb, then repeated it with cut-copy-paste.
Using Studio for Windows, I’m finding:
Ctrl+A selects all items, all plates.
Ctrl+Shift+A also selects all items, all plates. This key combo is not in the “?” list of shortcuts.
Right-click on a active plate, then Select All to select all items on only that plate.
That will do the same as Ctrl + A because that is how the key combinations work. Unless a developer chooses something specific for the Shift modifier, it does whatever the non-shift modifier does. You can test this with Ctrl + N & Ctrl + Shift + N - both perform the new option.
THe same is true on the macOS platform.
That isn’t a keyboard shortcut which was the original question.
The shortcut doesn’t exist at the moment. It is a feature request (FR).
Thanks for that. I didn’t knew ^^`. It will helps a bit while I’m waiting for this FR to be implemented
This still seems to be the only way to do this. At least I found this post 
