To focus on only the selected bones in Spine, you can utilize a combination of features to reduce clutter and improve visibility. While Spine does not have a direct equivalent to Blender's Shift + H command for hiding unselected bones, you can achieve a similar effect through the following methods:

1. Hide Unnecessary Bones: You can manually hide bones that are not needed for the current task. Right-clicking a bone's visibility dot will hide that bone and all its children, which can help reduce clutter (source). Additionally, pressing H will hide selected bones, and ctrl+H (or cmd+H on Mac) will show all hidden bones and slots, allowing you to quickly toggle visibility (source).

2. Use Selection Groups: Spine allows you to create selection groups by selecting bones and pressing ctrl (or cmd on Mac) plus a number (1-9) to save the selection. You can then recall this selection by pressing the corresponding number key, which can help you quickly focus on specific bone chains or groups without manually selecting them each time (source).

3. Isolate Selection: While not directly mentioned in the provided contexts, Spine's workflow can be optimized by isolating selections and working with visibility settings to focus on the elements you need. This includes using the tree or dopesheet to select and hide/unhide bones efficiently.

Although Spine does not currently offer a quick selection feature for bone chains similar to Blender's L key, you can use selection groups and visibility toggles to manage complex rigs effectively. These methods can help streamline your animation process by focusing on the necessary bones while reducing on-screen clutter.

belpetr
Thanks for your input! Not just for bones, but the idea of being able to hide anything other than what is selected has been on our roadmap for some time: EsotericSoftware/spine-editor604

Another useful feature is the use of a quick selection of a chain of bones using the L key.

You can set a hotkey to Select - Descendant Bones for this purpose: