When you create a Toaster project, you must select the release you want to use (for example, YP 1.7). From then on, the layers Toaster makes available for selection via layer sources are the ones from the branch compatible with the selected release (in the case of the OpenEmbedded layer source, the dizzy branch). However, if a certain layer does not exist in the branch for my selected release, I would like to select a layer from another branch to add to my project. For example, in the case of the OpenEmbedded layer source, chances are that a layer from the master branch will work with the latest Yocto Project release.
This should include the ability to set a tag or commit as well, effectively "freezing" the layer revisions.
Clearing 2.0 milestone
This becomes important when interacting with devtool, so tentatively moving to 2.2. See bug 9229 for some background.
This can be very unstable. The new Layer Import covers this if the user really wants to do it.