View mode settings: Includes 5 modes as the figure. The original button is set as a 'Push to view' button, push it to show the original and release to previous mode. Double click the 'color as background' button for changing colour.
Polygon modification:The default status us 'Substracting' mode showing cursor '-', means anything selected will be treated as background; Press 'Shift' to turn into 'Adding' mode with a'+' flag. Adding mode means the select area will be treat as foreground. Press 'Ctrl' will turn polygon tool to 'Free select' tool.
Free paint modification: Choose a brush to add or subtract to/from foreground. Press 'Shift' for the subtracting mode, which works as an eraser. Set the opacity of the brush to a low value will make the manually painting more easily to control.
Locally re-matting tool: This tool will matting a local area, with the selected local foreground and background colours around. It includes 2 statuses, colour sampling status and matting status. In colour sampling status, moving cursor to foreground where 'F' shown on cursor, then clicking collects a foreground colour as candidate. Moving to the background where 'B' shown on cursor then clicking collects a background colour as candidate. You can collect 6 pair candidates at most. If at least 1 pairs of candidates is collected, the tool enters matting status. In matting status, paintings on edge will re-matting the area by choosing out the best candidates pair and calculating the alpha value with it. Press 'Shift' to swap to colour sampling mode, "right-click" to reset all candidates and select again.
Desaturation tool: When the edge contains the colour from background you can use this tool to remove the colour. First, click the colour to specify the value, then paint to remove saturation. Right click to reset the colour.
Feather tool: Paint to feather the mask.