Supporting the Mac OS menubar in JavaFX

[steve.x.northover at oracle.com]

Hello all,

How about an API in Stage where you set the menu bar for the stage?  
This is the menu that you wish to be native and the application very is 
clear about this.  There can only be one real menu bar on Windows.  
Application code can ask for the menu bar and add items to it.  If you 
have a property, application code needs to do the same search that FX 
does to determine if there is an active menu bar.

Here is what I think about focus: On the Mac, when a stage gets focus, 
it sets the native menu bar.  When it loses focus, it clears the native 
menu bar.  Retaining the menu from the previous stage is unlikely to be 
the right thing to do as an application can have many different stages 
around and only the application can know whether the current menu bar 
applies to a stage.

Steve

On 14/12/2011 6:31 PM, Jonathan Giles wrote:
> Hi All,
>
> Here's an update from the UI controls team as to how we see the native 
> Mac OS menubar support working. Your thoughts are appreciated.
>
> After discussing it again today, we think that the approach suggested 
> by Richard in an earlier email in this thread makes the best sense, in 
> terms of modularity and code cleanliness. I'll explain this further 
> shortly...
>
> The thinking is to add a new property to javafx.scene.control.MenuBar. 
> We haven't settled on a name, but it's something along the lines of 
> 'native', 'global', 'globalMenuBar', 'screenMenuBar', or 
> 'applicationMenuBar'. Whatever property name we use, we'll expand it 
> out to have the usual set*/get*/*property methods. This would be the 
> only public API we end up adding for native menubar support. For the 
> remainder of this email I refer to this property as 'native'.
>
> This property will by default be true, indicating that on platforms 
> where we support native integration, it'll happen by default.
>
> On a platform that supports native integration, we'll find the 'first' 
> MenuBar in the scene that has the 'native' property set to true. We 
> can't guarantee that we'll find necessarily the physically top-most 
> MenuBar as that is really a matter of how the scenegraph is laid out. 
> Of course, this is only a problem in situations where the scene 
> contains multiple MenuBars where 'native' is true in more than one of 
> them, which we hope won't often be the case. If a Scene does have 
> multiple MenuBars with 'native' set to true, the behaviour is 
> undefined. If the wrong MenuBar is made native, you can help provide a 
> hint by setting 'native' to false in the relevant place(s).
>
> We'll also hook into the Stage and listen to the relevant events, such 
> that when a Stage gains focus, we'll switch in any native menubars 
> found in the scene of that stage. If no relevant MenuBar is found, 
> then we can either retain the MenuBar from the previous stage, or null 
> it out. I'm going to assume the former is by far going to win this 
> vote, but feel free to surprise me.
>
> Using this approach, developer code should be cleaner. Your user 
> interface should position a MenuBar where it makes sense for your 
> application, regardless of the operating system (normally at the very 
> top of your scene). On platforms where native integration is 
> supported, the JavaFX-rendered MenuBar will not be rendered (although 
> it'll likely remain in the scenegraph as a no-op control). If the 
> 'native' property changes, we'll flick between the native and 
> JavaFX-rendered MenuBar as expected. This approach means there is no 
> operating system dependent code in your user interface.
>
> As I mentioned - we're totally open to discussion on any of these 
> points. Any thoughts?
>
> -- Jonathan
>
> On 10/12/2011 8:56 a.m., Jonathan Giles wrote:
>> Hi all,
>>
>> One of the things we're planning to support in JavaFX 2.1 is the 
>> native Mac OS menubar. This email is intended primarily to discuss 
>> the API one expects to see to set a MenuBar in the native Mac OS 
>> menubar area. Your feedback is sought and will be very much appreciated.
>>
>> The current thinking is that Application feels like the right place 
>> to specify a global, application-wide javafx.scene.control.MenuBar 
>> on. It could be assumed that if a developer were to set this 
>> property, and the operating system upon which the end-user was 
>> running the JavaFX application was Mac OS, that the menubar will be 
>> displayed using the native Mac OS menubar. Of course, if a developer 
>> wants a cross-platform look and feel, they could just place the 
>> MenuBar in the stage as per usual and it would display as it 
>> currently does. This approach opens up a number of questions and issues:
>>
>> 1) What happens in the case of the end-user being on Windows? Is the 
>> Application.MenuBar ignored, or is it automagically added to the main 
>> Stage? (I would argue for totally ignoring it....but that leads to 
>> the next point).
>> 2) This approach means there needs to be operating specific code in 
>> the UI to test whether a non-native MenuBar should be added (in the 
>> case of Windows, for example). This starts to clutter the UI code, 
>> and without careful consideration by the developer may result in 
>> needing to duplicate their MenuBar code. Is there a better approach?
>>
>> Another place to specify a MenuBar would be on Stage, rather than (or 
>> in addition to), Application. Having a MenuBar property on Stage 
>> would allow for the MenuBar to change based on the currently focused 
>> Stage - but I'm not certain this is desirable or even the expected 
>> behaviour of Mac OS. Therefore, I'm thinking that this is not likely 
>> to happen unless we hear otherwise.
>>
>> Like I said, we're at a very early exploration point in this process. 
>> The controls team is very keen to hear feedback from the community, 
>> as well as from the owners of the Application API, and the Mac OS 
>> experts on this list.
>>
>> Thanks,
>> -- Jonathan