This requests to make this visible to the user.
Actually the precise semantics of this function depend on the window system currently in use, and if you don't have a multi-windowining system this function may in-fact do nothing.
This function will implicitly allocate the given this framebuffer before showing it if it hasn't already been allocated.
When using the Wayland winsys calling this will set the surface to a toplevel type which will make it appear. If the application wants to
set a different type for the surface, it can avoid calling show and set its own type directly with the
Wayland client API via
<note>Since Cogl doesn't explicitly track the visibility status of onscreen framebuffers it wont try to avoid redundant window system requests e.g. to show an already visible window. This also means that it's acceptable to alternatively use native APIs to show and hide windows without confusing Cogl.</note>
The onscreen framebuffer to make visible