Popup: Replace Bounds input pin by just the Position?

[antongit]

At the moment the Popup widget has Bounds input pin, that is channel. Internally we set the bounds like that:

      if (boundsChanged)
      {
          ImGui.SetNextWindowPos(bounds.TopLeft.FromHectoToImGui());
          ImGui.SetNextWindowSize(bounds.Size.FromHectoToImGui());
      }

Unfortunately, somehow the SetNextWindowSize doesn't work as expected for the Popup (it does for the Modal), it works for one frame, and then the Popup jumps back to its somehow internally calculated size. See the HowTo Popup, HowTo Modal Popup. Maybe I'm missing something... SetNextWindowPos works as expected.

@azeno @gregsn: What do you think?

[azeno]

If it doesn't work, then yes, get rid of it. Or is it simply the changed check which makes trouble? As an alternative we could also make two pins for position and size and use Optional<Vector2> as type, so if not specified it's up to ImGui to do the layouting and if specified that value is taken, and set every frame.