I have a sight problem -- Retinitis Pigmentosa -- resulting in very narrow vision (but good central vision). As a result I sometimes lose the position of the mouse cursor on screen, even though I have chosen the biggest icon for it and enabled mouse trails.

Sometimes this results in my accidentally moving a single tab out of the one larger dock which i prefer, and it goes elsewhere on screen. I now have one main dock and two others each with a single misplaced tab elsewhere.

I desperately need to put those docks back, merging all tabs into one dock.

I simply cannot find a way to do it. I managed once, somehow, but cannot reproduce this success.  I cannot find any help or documnetation on how to do such a thing, so I assume the designers thnk it is "intuitive" -- but I assure you it isn't. I've tried all of the actions which seem reasonable to me, but the usual result is that one dock sits under the other, unreachable except by luck!

Please help!

Regards
Pete Dowson