RFE: Merged selection
Using Inkscape 0.92, I wasn't able to figure out how to have a "merged selection", being able to select elements in visible layers without having to worry in which layer they were.
The use case was trying to centre items over different background items. The background items were in a separate locked layer. Being able to select the item in the top layer and in the bottom layer easily so I could centre them would have been very useful. The work around was to use the "Objects" dock to select the item that weren't in the current layer.