Double Click
Add a new blob at the cursor position.
CtrlA
Select every blob on the canvas.
CtrlCV
Copy and paste selected blobs.
Del
Delete the selected blob or blobs.
Scroll
Change radius of the selected blob or blobs.
ShiftScroll
Adjust core size / hardness.
CtrlScroll
Adjust brightness.
CtrlShiftScroll
Cycle the selected blob color.