System - Window for the $ graphic not handled correctly when the System has transparency

[Mimigris]

Name of the game:

Yume 2kki version 0.120b. (Note that said graphic got edited in version 0.120c, hence why I'm precising this version, but the issue is present for both).

Player platform:

Windows, 64 bits continuous build version of the Player.

Describe the issue in detail and how to reproduce it:

Likely related: #2961

When a $ message is displayed with this System graphic in Yume 2kki (e.g. when using a vending machine), the transparency for the window will incorrectly be set compared to the RPG_RT, making the window shown as transparent while it should not be the case.

System before version 0.120c:

RPG_RT:

EasyRPG:

System in version 0.120c:

RPG_RT:

EasyRPG:

[Ghabry]

The transparency must come from the opacity setting of the "Show Message Option" command but unsure why RPG_RT renders this different. Maybe some timing thing like #2932