The feature to display multiple objects in the UV and Image Editor was
added in 24d08e0bae.
This commit did not account the multi-edit mode feature, where there may
be more than one object currently being edited, causing some UVs to
display with a faded opacity.
To fix this, introduce a new `eObjectInfoFlag` flag to indicate this
state, populate it when syncing the object, and use the flag inside the
relevant shaders.
Pull Request: https://projects.blender.org/blender/blender/pulls/141254
62568d16e5