This fix enables the user to disabled the rounded corners in the widgets.
I misread the comment, so I will get that fixed and update.
I asked on IRC and it got mentioned.
< bzztploink> StigAtle, /* flags 6 and 7 were old flags that are no-longer used */
you misread that comment, it means 6+7 are used in the past, and are excluded from use,not that they are available.
Hey @stig atle steffensen (stig_atle),
we had a different approach for the rounded corners option, see T45025. Blender's usability already suffers from too many options, we need to be careful about adding new ones (and we need to consolidate old ones).
Thus, not accepting this patch, but thank you nevertheless :)