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I'm not seeing a way to set up a Canvas texture to use a translucent background. It starts off solid black and all the various "Clear" functions do a solid-color fill, ignoring the alpha value of whatever color gets passed in. This limits its usefulness for many applications (menus, etc.).

I believe the canvas texture itself already have the alpha channel, so this boils down to the Clear functions ignoring the alpha channel. If it could be altered to use a renderstyle with a SRCALPHA blend rule then it would probably apply the alpha.

I second this, because the lack of translucency currently significantly limits the application for these.