Fix show command for Qt backend to raise window to top

[nmichaud]

When running ipython in pylab mode using the Qt4 backend (either from qtconsole or the ipython notebook), calling show() does not raise the window to the front.

[mdboom]

Related to #596

[pelson]

Agreed. The feature request is in #596. If there is a specific ipython issue, it should go into the ipython issues tracker.

[pelson]

Apologies @nmichaud. I wonder if I closed this issue too soon (I'm not sure I had seen it was a PR rather than a repeat feature request). The implementation would need a bit of a review, but the functionality is definitely desirable.

@mdboom feel free to re-open if you think necessary.

[efiring]

As I noted in #596, I don't think that it is always desirable to have the figure window pop up, potentially on top of whatever else one is working on, and/or potentially stealing focus.
My reading of http://www.riverbankcomputing.co.uk/static/Docs/PyQt4/html/qwidget.html#raise is that the PR here is more limited than what is requested in #596, in that it involves only the Qt application, not the OS window manager. Perhaps addressing #596 will require two levels, one like this at the Gui toolkit level, and another at the OS window manager level--though presumably implemented via facilities provided by the toolkit.

[dmcdougall]

@efiring I think the correct method to use is this one.

[efiring]

@pelson, I think that depends on what one is trying to accomplish; it might be what raise_ does, or it might be what activateWindow does, or it might be both. I would be strongly opposed to having show always call activateWindow, but having it always call raise_ might be acceptable. In any case, I think the right way to approach this is by seeing to what extent all the gui toolkits have methods like these that mpl might be able to wrap in a gui-neutral fashion. I am not a fan of tacking little behavior tweaks (or additional toolbar buttons) onto individual toolkits. qt4 seems to invite this, and is already the oddball of the bunch. I am not opposed to all such attempts at optimization, but I think a conservative approach is advisable.

[dmcdougall]

Wait, did you mean @pelson or did you mean me? I think you meant me.

Yes, my suggestion was purely a behavioural one. I did not mean to imply it should always be called by show. In fact, I find it quite inconvenient to always steal focus. It should be up to the user to decide. Sorry for the confusion.

[efiring]

@dmcdougall, yes, I was confused as to who I was replying to; I see we are in agreement as to the evils of forced focus stealing!