The manual only mentioned to LMB to remove items from the queue - but did anybody know, you can also drag your items up and down for priority production of an item while retaining(!) production status of an already say half manufactured item (blue bar) ? Very happy to discover this, because remove only was not fun, if you needed something more urgently and had to later add it again in lowest spot.
Using drag items, you can also (somewhat, to an extend) control material expense rate. You may have noticed that with more expensive items, material expense rate rises. Now if you don't need that item next, but rather want to keep up production time with material income or even boost material income for an amount of time, just drag some low value item to the top spot in the queue, thus lowering material expense.