By user request a new version of Eneroth Visual Merge has just been published.
The new versions adds a workaround for an issue related to SketchUp 2018 section fills. The way fills are currently implemented, hiding a face defining the boundary of a fill removes the fill. I am not very pleased with this behavior as hiding a face in my view should merely hide the face, not change/destroy the volume defined by it.
The new version of the plugin adds an option under Extensions > Eneroth Visual Merge > Options > Hide Faces when Merging controlling whether the touching faces should be hidden.
Unfortunately, not hiding the faces has the side effect of them bleeding through the the outer faces. This is why the extension is hiding the adjacent faces in the first place and not merely the collinear edges. This is also why the old behavior is the default setting.
As there is no-one-size-fits-all solution for this problem it had to be a user setting.
When using Hidden Line Face Style, which is common for drawings, the issue with faces bleeding though ceases as interior and exterior faces all look the same. When aligning the camera orthogonally to the faces, also common for drawings, this isn’t a problem either as the faces don’t bleed through when viewed in these angles.
The setting doesn’t affect already merged groups/components. To update them, select them, reset merging and merge anew.
The setting is saved on a per model basis to best allow you to work on a project on multiple computers. To change the setting for all newly created modules you can change it and then save the model as a template.