This section of the EgyGene GelAnalyzer4 software: Image Analysis part includes the necessary commands to draw a tilted lane or a lane with un-equal widths seems to be as a trapezoid (or something similar) instead of its traditional rectangle shape.
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This command shifts the shape of a pre-defined lane to trapezoid or something close to it. To draw a tilted lane follow the next steps:
A. Press the button "Tilted Lanes".
B. Move the mouse cursor to any of the four corners of the sample (the upper right corner - the upper left corner - the lower right corner - the lower left corner) untill the cursor changes to the shape of an arc or a half-circle.
C. Press the left mouse button and hold it down (the cursor will changed to a full circle).
D. Drag the selected corner to the new position, then release the mouse button.
Tutorial video
(Set the video quality to 720 to be clear)