Line Cut shows empty values for NaN-based float objects, depending on line start

[M. Gronle]

If a dataObject, with multiple NaN regions is showed in a itom2dqwtplot and a line-cut is shown, this linecut sometimes shows valid pixels, but sometimes does not show anything. This seems to be related to the start point of the mouse. If the start is within a valid area of the original object, the line cut seems to be ok, if the mouse starts somewhere in an NaN area, it shows nothing although the mouse if moved over the valid areas. Even if the line plot is already showed and a new line is created by a new mouse click, the plot sometimes does not show anything at all.

Any exemplary object is attached.

[M. Gronle]

itom1dqwtplot: fixes issue #44: the scales in a line plot, that contains no or only invalid values, are properly shown (fun fact: minValue > maxValue yields an invalid x-axis. Strange. But solved now)

→ <<cset 9b34e111f930>>