ContainerScreenEvent$Render$Background runs after renderables are drawn

[Fuzss]

Minecraft Version: 1.20.4

Forge Version: 49.0.26

Description of issue:
In 1.20.1 the order in AbstractContainerScreen::render used to be:

• AbstractContainerScreen::renderBg
  • Screen::renderBackground
    • Draws the black transparent background overlay
  • Draws the menu background sprite
• ContainerScreenEvent$Render$Background (Forge event)
• Screen::render (super method)
  • Draws the screen renderables
• ...

In 1.20.2+ AbstractContainerScreen::renderBg has been removed in favor of using Screen::renderBackground which is now implemented in subclasses. Therefore the order in AbstractContainerScreen::render has changed to:

• Screen::render (super method)
  • Screen::renderBackground
    • Draws the black transparent background overlay
    • Draws the menu background sprite
  • Draws the screen renderables
• ContainerScreenEvent$Render$Background (Forge event)
• ...

This new behavior makes it impossible to render background sprites which are drawn behind renderables like buttons & widgets.
For intentionally rendering sprites in front of renderables ContainerScreenEvent$Render$Foreground already exists.

My suggestion for restoring the 1.20.1 behavior would be to move firing ContainerScreenEvent$Render$Background to Screen::render (with an instanceof check for AbstractContainerScreen) right in-between the call to Screen::renderBackground and screen renderables being drawn.

Moving ContainerScreenEvent$Render$Background to AbstractContainerScreen::renderBackground is not a good option as it would fire after the black transparent background overlay is drawn, but before the menu background sprite is.

[LexManos]

Instanceof is rather costly especially for things done every frame.
Better option would be to change AbstractContainerScreen to call renderBackground instead of render. And manually render the renderables as they are an accessible field. It'd make noticing changes a bit more painful during updates but it keeps the logic and patch to one place and doesn't have the performance cost of instance checks.