Mari 4.6v4 docs:

Painting Functions

A list of functions and shortcuts for painting and baking paint can be found in the table below.

Function	How to access it	What it does	Opens this dialog box	Notes
Undo all unbaked painting	• Menubar \| Painting > Clear Painting • Toolbar \| • Mouse \|	Undo all painting not yet baked into the model (still in the paint buffer).		For the mouse gesture: press and hold \, click and drag in the direction indicated. (A thin red line traces gestures onscreen.)
Undo	• Menubar \| Edit > Undo • Keyboard \| Ctrl/Cmd+Z • Toolbar \| • Mouse \|	Undo the last action.		For the mouse gesture: press and hold \, click and drag in the direction indicated. (A thin red line traces gestures onscreen.) See also the History View Palette.
Redo	• Menubar \| Edit > Redo • Keyboard \| Ctrl/Cmd+Y • Toolbar \| • Mouse \|	Redo the last (undone) action.		For the mouse gesture: press and hold \, click and drag in the direction indicated. (A thin red line traces gestures onscreen.) See also the History View Palette.
Bake painting into the model	• Keyboard \| B • Menubar \| Painting > Bake • Mouse \| • Status bar \|	Saves the painting as part of the project.		For the mouse gesture: press and hold \, click and drag in the direction indicated. (A thin red line traces gestures onscreen.)
Show or hide painting	• Keyboard \| .	Shows or hides the contents of the paint buffer (that is, the unbaked paint).
Show or hide paintable areas (not currently masked out)	• Menubar \| Painting > Toggle Mask Preview • Keyboard \| , • Painting Palette \| Projection Settings \|Mask Preview \| Mask Preview Enabled	Shows or hides the current masking (including all masking currently turned on - the edge mask, channel mask, ambient occlusion mask, depth mask, and backface mask).		When this is on, this shows paintable areas normally, and unpaintable areas are colored.
Save current painting as a file	• Menubar \| Painting > Save Painting	Saves the current unbaked paint (the contents of the paint buffer) as an .exr file.	Save Window Painting	Saves the paint buffer as an .exr file, and puts it in the Image Manager Palette.
Load previously saved painting files	• Menubar \| Painting > Load Painting	Loads an .exr file and projects it onto the model as the current painting.	Load Window Painting
Draw straight line between two points	• Mouse \| Click, then Shift+click	Draws a line with the current brush between the two selected points.
Draw straight line horizontally or vertically	• Mouse \| Shift+click and drag	Constrains painting to straight horizontal or vertical lines.
Toggle Last Brush Tip	• Mouse \| • Keyboard \| N	Switches to the last brush tip used.