[Libreoffice-ux-advise] Bug 56973 - UI: Copy / Paste sole sheet of a spreadsheet wrongly looks inactive

Hi,

I have a design question in
 <https://bugs.freedesktop.org/show_bug.cgi?id=56973>.
Is there any style guideline concerning items greyed out in  UI? 
Sometimes we have check boxes greyed out with a checkmark, and it means 
"Check is mandatory because of other properties, you can't unselect it". 
For example

A) Sometimes there are items with no influence in the current
   situation, there greyed out means "Does not matter"

B) In Draw menu 'Format -> Position and Size - Protect Size.'
If you select 'Protect position', 'Protect Size' will be checked 
automatically and is greyed out because you can not modify this.

My opinion:
a) Do not show checkboxes without function
   - so remove inactive items from Draw menu
     'Format -> Text - Text'
b) Show checkbox and ittem text greyed out if
   shown status is mandatory
c) Radibuttons: Show selectable and/or selected
   status in normal black, only positions what can
   not be selected in Grey.
   For example in the bug that might be not
   important, but for selections with more than
   2 button positions to me this seems most intuitive.
   For example see Print dialog, there are 3 radio button positions,
   and "Selection" is greyed out and inactive if nothing is selected
   in document. So it seems consequent to me to show the mandatory
   position in normal black and the impossible one greyed out if only
   2 positions are in the dialog.

Are there any UI style guidlines for this? Can you please leave a 
conclusion in the Bug?

CU

Rainer