In Transform mode, press Shift to drag corner and constrain scale

`↑ Shift`

All hotkeys for Autodesk SketchBook (Mac)

Marking menu Marking menu 1	`1`
Marking menu Marking menu 2	`2`
Marking menu Marking menu 3	`3`
Marking menu Marking menu 4	`4`
Marking menu Marking menu 5	`5`
Marking menu Marking menu 6	`6`
Marking menu Interface controls	`1` then `Mouse right click`
Marking menu Tools	`2` then `Mouse right click`
Marking menu Brushes	`3` then `Mouse right click`
Marking menu Colors	`4` then `Mouse right click`
Marking menu Edit	`5` then `Mouse right click`
Marking menu File	`6` then `Mouse right click`
Tools Previous frame (animation mode)	`,`
Tools Previous frame (animation mode)	`<`
Tools Adjust size (brush mode)	`B`
Tools In Transform mode, press Shift to drag corner and constrain scale	`↑ Shift`
Tools Play/Stop	`⤶ Enter`
Tools Add layer (layers mode)	`⌘ Cmd` + `L`
Tools New (menu)	`⌘ Cmd` + `N`
Tools Invoke Perspective tool (perspective mode)	`P`
Tools Invoke Lasso selection (selection mode)	`L`
Tools Invoke Symmetry X (symmetry mode)	`X`
Tools Transform layer	`V`
Tools Hide UI (UI)	`T`
Tools Hide UI (UI)	`⭾ Tab`
Tools Zoom / rotate / move canvas	`Space`
Tools Open	`⌘ Cmd` + `O`
Tools Save	`⌘ Cmd` + `S`
Tools Save As	`⌘ Cmd` + `↑ Shift` + `S`
Tools Print	`⌘ Cmd` + `P`
Tools Exit	`⌘ Cmd` + `Q`
Tools Undo	`⌘ Cmd` + `Z`
Tools Redo	`⌘ Cmd` + `↑ Shift` + `Z`
Tools Cut	`⌘ Cmd` + `X`
Tools Copy	`⌘ Cmd` + `C`
Tools Copy Merged	`⌘ Cmd` + `↑ Shift` + `C`
Tools Paste	`⌘ Cmd` + `V`
Tools Select All	`⌘ Cmd` + `A`
Tools Deselect	`⌘ Cmd` + `D`
Tools Invert Selection	`⌘ Cmd` + `↑ Shift` + `I`
Tools Adjust Opacity	`O`
Tools Adjust Slant	`/`
Tools Increase brush size	`]`
Tools Decrease brush size	`[`
Tools Press ‘Alt’ before selection, remove mode	`Alt`
Tools Color picker	`I`
Tools Swap between two brushes	`S`
Tools Add Group	`⌘ Cmd` + `G`
Tools Merge with below	`⌘ Cmd` + `E`
Tools Delete key to delete last point, Double-click to confirm	`Del`
Tools Fit to View	`⌘ Cmd` + `0`
Tools Actual size	`⌘ Cmd` + `Alt` + `0`
Tools (nine) Rotate canvas left	`9`
Tools (zero) Rotate canvas right	`0`
Tools Hide Lagoon	`⌘ Cmd` + `J`
Tools Toggle Title bar on/off	`⌘ Cmd` + `Alt` + `J`
Tools Preference	`⌘ Cmd` + `,`
Tools Next frame	`.`
Tools Next frame	`>`
Tools Previous keyframe	`↑ Shift` + `,`
Tools Previous keyframe	`↑ Shift` + `<`
Tools Next keyframe	`↑ Shift` + `.`
Tools Next keyframe	`↑ Shift` + `>`
Tools Add keyframe (on next frame)	`Alt` + `“.”`
Tools Invoke Rectangle Selection	`M`
Tools Key Arrow key to move pixel	`Arrow`
Tools Exit the fill tool	`Esc`
Tools Click the start point to confirm or Enter key to confirm	`Mouse left click`
Tools Invoke Crop tool	`C`
Tools Snap or not	`D`
Tools Invoke Symmetry Y	`Y`
Tools Ruler	`R`
Tools Ellipse	`E`
Tools French Curve	`F`