Use this panel to graphically edit the first component of the selected dashed line. The black and white flags represent sections of the dashed line.
Each black flag represents the end of a dash in the line, the length of which can be edited either by dragging the flag in a horizontal direction, or by editing its value in the Dash edit fields.
The little white flags represent the gap between each dash section, and can be edited similarly.
The values in the numerical input boxes use the units defined in Options > Project Preferences > Working Units.