If the value of GuiIngameForge.left_height is not set to 39 directly before drawing the health bar, Mantle ignores the actual value and just draws the health bar in the same location. This causes an incompatibility with my mod Better HUD: mccreery/better-hud#30, which modifies the value of left_height.

Repro:

• Install Mantle and Better HUD
• Open the Better HUD menu with U and disable everything
• Enable just the health bar

You'll see that the health bar shows offset from the bottom of the screen, even though left_height is set so that it should render at the bottom.