BitBucket: https://bitbucket.org/namida42/neolemmixplayer/issues/13/ctrl-a-instead-of-just-a-for-select-all
Just a simple suggestion, pressing ctrl+A should select all terrain and objects. This is a standard keyboard shortcut and is useful for repositioning the whole level along with other things.
Just press "A" without "Ctrl" and everything gets selected.
Oh, I didn't know that, though that shows that Ctrl+A should at least also work as that's what is used in every other tool I can think of and therefore is what I'd think to try. Especially considering the fact that Ctrl+C/Ctrl+V are used for copy/pasting rather than just C or V
If you're wanting to move the whole level, I suggest using the "Shift Level" option in the Edit menu. This adjusts things like the screen start position and VGASPEC position as well as the pieces.
Giving Ctrl+A a select all function makes sense, so I'll put that in. Just keep in mind that it'll (in most cases) be inferior to the Shift Level option.