Confusing staff selection for manual adjustment

I truly appreciate the level adjustments which can be made in Engraving mode. However, there is one niggling annoyance I’ve notice (which might be just me, but bear with me).

If I select multiple staves to adjust with Ctrl+click [Win7 sytem], I CANNOT release the last stave clicked before dragging. I must keep that final stave “clicked” so as to not “disengage” the previously clicked staves. Typically, when “selecting items” one would click all the items [staves] to be selected, THEN drag as needed. If I do that, all the previously selected staves are “unselected”, and only the last stave I clicked moves. I have to remember to click several staves, then click-and-HOLD-and-drag the final stave so that ALL staves will move.

This seems counter-intuitive to me. I want to select all the staves to be moved first, then move them. Am I doing something wrong, or is this the intended action?

I use the arrow keys to move the staves after selecting them.