Hello everyone,
After having spent 24h plus on a very annoying issue... here I share.
the issue: Whatever the designer variant I used, whatever the settings (manifeste file, attributes, etc, etc ...) I could not make my Activity cover the entire screen.
the Solution: Samsung Tablet have a unique feature called "Devx" that enables broadcating the table screen onto TVs, PCs screens. If this feature is ON, the Activity screen is restricted to a portion of the screen.
So, disabling this Feature solved my issue
Cheers,
noega33