Make it possible to add spacers to all selected staves and filter selection by spacer
Sometimes one needs to add spacers to all staves in order to increase uniformly the distance between staves. An example, when hiding empty staves and there is no room for an extra system. Currently one must select the staves one by one and add the spacer.
It would be nice to be able to select all the required staves and double click the spacer from the palette to insert all the spacers at once.
Once the spacers have been added, one needs to select them all so that with single change in the inspector, the correct distance can be achieved. Currently one has to select them one by one since spacers are not listed in the selection filter.
It would be interesting that such filter were available.
Combining both features, it would be easy to change the stave distance in a few steps.