Supporting the Mac OS menubar in JavaFX

[Jonathan Giles]

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