Libui: Implement a way to get/set window state

[parro-it]

With window state I mean if it is minimized/maximized

[andlabs]

Again, I'd like to meter what the usefulness of this is. Anyone?

[parro-it]

Some example of use:
For minimization getter: an app could to stop doing something computationally heavy when the window is minimized.
For minimization setter: the window could be put in normal state and focused when something happens

For maximization getter: UI could be layed out differently when window is maximized. For example some controls should be made visible/unvisible (this use case could involve an event to notify window size change as originally suggested by @PaulBGD)

[PaulBGD]

I honestly don't think this is _super_ useful (such as what's the difference between a maximized window and a window that takes up the entire screen), but I do think having an event for when the maximize/minimize buttons are clicked would be useful (sort of like the onClosing event - you could add stuff like maximize makes it fullscreen and stuff.)

[parro-it]

@PaulBGD no _super_ useful, I agree, but I already used them from time to time using other toolkits...

[parro-it]

Another use case could be to save window state on app closure, and then restore same window status, position and size on subsequent app start. This use case will involve also getter/setter for size and positiobn

[andlabs]

Fullscreen implemented in the meantime