Selecting, moving and splitting

Click a region to select it; Shift+click adds or removes regions. Clicking empty lane space deselects. Ctrl+A (Edit › Select All) selects all regions.
With a group whose Editing setting is on, clicking a region also selects the regions at the same place on the other members.
Drag across empty lane space to draw a rubber band: every region it touches is selected. Shift+drag adds to the selection. A click without dragging still deselects.
Right-click a region › Select › All on Track, All Following on Track, or All.
Edit › Select picks regions by criteria (All Following, Inside Locators, Muted, Same Colored…); see Arranging commands.
Ctrl-drag (⌘-drag on macOS) draws a marquee, a time range across tracks, instead of selecting whole regions, while the Ctrl-click Tool is the Marquee (the default); see Tools and the marquee.
Alt+drag (Option-drag on macOS) a selection to copy it: the originals stay put, the copies are drawn where they’ll land and become the selection, and the copy is one undo step. Some Linux window managers use Alt+drag to move windows; if that happens, use Copy and Paste, Duplicate or Repeat, or change the window manager’s modifier.

Moving, trimming and snapping

The pointer changes over a region’s hot zones:

Where	Drag to
The body or the name bar	Move the region (and the rest of the selection). Drag up or down to move it to another track of the same kind.
Lower left or right edge	Trim the start or end.
Top left or right corner, below the name bar (audio)	Set the fade-in or fade-out length.
Top right corner of the name bar	Set where a loop stops (see Loops).
The gain handle at the top centre of the name bar (audio, shown on hover)	Change the region gain (see Gain and reverse).

Moves, trims and loop ends follow the Snap setting (Smart, Bar, Beat or Off). Smart snaps to sixteenths, beats or bars depending on the zoom. Fades are never snapped.
Across tempo changes, a snapped move counts in bars and beats: the region you drag snaps to the grid where it lands, and the others in the selection keep their distance from it in bars and beats, so a region dragged from a 120 BPM section into a 90 BPM one still lands on its beat. Alt-drag copies do the same. With Snap off, the others keep their distance in time.
Drag below the last track to make a new track: a dashed lane appears under the last track with the region on it, and on release a new track of the same kind (audio or software instrument) holds the region, with the source track’s settings, as Move to New Track, but below every track and outside any stack. Each source lane of a selection that falls past the end gets its own track; regions still landing on tracks move as usual. Alt-drag copies do the same. It’s one undo step, and the automation stays on the source track.
A moved region comes to the front, so it plays over whatever it now overlaps.
The Drag mode decides what happens to the regions an edit overlaps or leaves a gap between; see Drag modes.
Move Automation with Regions (Settings › Editing): with Always, moving a region along its track (drag or nudge) takes the track’s automation under it along, replacing the automation where it lands; the place it left is bridged with a straight line, and the curve elsewhere is unchanged. Ask asks (Move / Don’t Move) when a move would take automation along. Never (the default) leaves automation where it is. Moves onto another track, copies, and neighbours that a Shuffle mode moves leave their automation behind.
Nudge: Alt+Left / Alt+Right move the selected regions by the Nudge Value (Settings › Editing; 1/16 note by default). A run of nudges is one undo step. A bar, beat or note value is counted through the tempo map: the first selected region moves by exactly that many bars or beats, and the others keep their bars and beats, across tempo changes too. A nudge by milliseconds moves every region the same time.
Snap Edits to Zero Crossings (Edit menu, also in the Tracks area’s and Audio Track Editor’s Edit menus; a key command with no key by default): with it on, splits, trims and range edits of audio regions (Split at Playhead, the Scissors, the marquee, the Audio Track Editor’s range actions and splits) move to the nearest point within 5 ms where the audio crosses zero (both channels summed) or is silent, so the cut doesn’t click. Each region is cut at its own crossing, so regions on different tracks split at slightly different points. Where there is no crossing within 5 ms, the edit stays where it was asked. MIDI regions and take folders are cut where asked. The setting is saved with the project and isn’t an undo step.
Regions on a frozen track can be selected but not changed.

Drag modes

The Drag pop-up in the Tracks area’s bar, next to Snap, sets the drag mode, as in Logic. It decides what moves, trims, nudges, deletes, pastes and Alt-drag copies do to the other regions on the track. It applies to audio and MIDI regions, each edit stays one undo step, and while you drag, the regions are drawn where the drop will leave them. The mode is saved with the project and isn’t an undo step.

Overlap (the default) leaves overlapping regions as they are.
No Overlap: of two regions an edit leaves overlapping, the one that starts first is shortened to end where the other starts, whichever of them you moved. A region dropped into the middle of a longer one cuts the longer one off there (its tail is not kept); a region dropped over the start of a shorter one is itself cut off there; a region dropped exactly at another’s start replaces it. Lengthening a region stops at its neighbour.
X-Fade crossfades audio regions that an edit leaves overlapping, over the overlap (type X), or over the Crossfade Time (Settings › Editing) where they just touch, and removes such a crossfade when an edit pulls the two apart.
Shuffle L keeps the regions on a track butted together. Deleting a region pulls the regions after it left by its length. Trimming either edge keeps the region’s start in place and moves the regions after it by as much as it grew or shrank. A region dropped on another goes before it if it lands on that region’s first half and after it on the second half, so dragging a region across its neighbour swaps the two; dropped in a gap, it snaps to the end of the region before it (or stays put if there is none). Regions after it move only as far as needed to make room, and the place it left closes up. Several regions dragged together move as one block. Pastes and copies go in the same way.
Shuffle R is the mirror image: deleting pulls the regions before the gap right, a trim keeps the region’s end in place, and a dropped region snaps to the start of the region after it (judged by where its end lands). Where that would push regions before the start of the project, the whole track’s regions move right instead.

Split and join

Split at Playhead (Ctrl+T, Edit menu or the region menu) splits the selected regions at the playhead (all regions under it when none are selected). Splitting a MIDI region keeps its controllers consistent: the right part starts with the values in effect at the cut.
Join (Ctrl+J) joins the selected regions on each track into one. MIDI notes are merged; audio is mixed, as it plays (newer regions winning), into a new file.