You can grey out a line manually:
PopH = uicontrol('Style', 'popupmenu', ...
'String', ...
{'one', '<font color="gray">two</font>', 'three'}, ...
'Callback', @myCallback);
But you have to care for blocking the callback in addition. You could store a logical vector in the UICONTROL's UserData:
set(PopH, 'UserData', [true, false, true]);
function myCallback(ObjH, EventData)
value = get(ObjH, 'Value');
userdata = get(ObjH, 'UserData');
if ~userdata(value)
% Reject callback.
% Perhaps: set(ObjH, 'value', find(userdata, 1));
return;
end
...
In this callback you see the reason, why popup menus do not allow disabled entries usually: Which line should be chosen, if the user selects a disabled line as alternative? And should the callback be triggered for the alternative choice, although the user did not select it intentionally?
