Default [Q] Disable hardware buttons

Hi,
I would like to disable the hardware buttons from my Galaxy Tab 3 7.0 since I already made the softkeys visible by changing the /system/build.prop file.

I found HowTo's for other Samsung devices. All of them proposed a modification of the /system/usr/keylayout/Generic.kl file by deactivating the mappings for the keys 139, 158 and 172 (see this thread). Unfortunately, this isn't working for my Tab 3.

Can someone give my advice in this topic?

Thanks in advance,
Greeny