Tooltip for disabled controls

steve.x.northover at steve.x.northover at
Fri Apr 5 13:09:01 PDT 2013

We can't start delivering events to disabled controls or we will break 
the universe (even for event filters).  Am I missing something?  There 
is potential for application code to start running that did not run in 
the past.  Suddenly, disabled controls in some applications that add 
filters to standard controls might start to do something when they did 
not in the past.

The reason that disabled tool items on native platforms have hover help 
is that they are lightweight (ie. on Windows, no HWND).  There is a 
separate API to disable them versus the API that disables a 
heavyweight.  So native platforms are relying on the implementation.  
You will notice that hover help dies not come for push buttons for 
example on Windows.

Whether hover help should be displayed or not is specific to the 
control.  For example, in tool bars, we want the hover help. However, 
when a tree is disabled, we don't expect hover help for the tree item.

The safest way to do this is to add new versions of the events that get 
delivered when the control is disabled.  Tool items can be changed to 
use the new events.  Tree items can be left alone.



On 05/04/2013 3:01 PM, Richard Bair wrote:
>>> So are the CSS rules designed such that disable will still be applied, or will the hover rules take precedence? We'd have to try it out.
>> I've tried. As I expected, controls fully rely on the events not being delivered. When I deliver events to a disabled button, the button stays grayed, but works normally - gets highlighted on hover/armed, gets pressed etc.
>> When I deliver the events to filters but not to handlers, everything looks fine on the first sight.
> I like this idea, lets continue pursuing it and see if it works out.
> Richard

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