Selection
Click Select shape or line
Shift+Click Add to selection
Ctrl+A Select all
Drag empty area Marquee select shapes and lines
Esc Deselect all
Connections
Drag from a point Connect to shape under cursor
Click a point, click a shape Connect in two clicks
O Toggle orthogonal/curved
Drag segment Move it
Drag bend Move the corner
Double-click bend Remove it
Drag label Move it
Double-click label Edit it
Double-click line Reverse direction