Library of Shapes?
Shapes and components should be separate. Glyphs are (or can) be made of components. Components are made of shapes. I shouldn't need to go to a glyph to copy a shape--I should be able to select from a list of stored shapes to create a new component (just like I can select a component to make a new glyph. I don't see a library of shapes.
"Components" in Glyphr Studio can either be a single shape, or many shapes. Components can also contain other components... from the tool's point of view, a glyph contains a stack of either components and/or shapes.
While you are on a Glyph, there is an Action called "Add Component Instance" (it's a green square with a + sign). This will bring up a list of your current components to add to that glyph. Additionally, entire glyphs can be used as components in other glyphs, so they are shown in the "Add Component Instance" dialog as well.
So, I believe the "Add Component Instance" function should work as your "Library of Shapes" - let me know if i'm not understanding correctly!