Version 6 release

• Undo/redo of all operations means recovering from mistakes and experimenting with options is painless
• Interactive Help Tutorial explains typical processing steps that apply according to image file type
• Checklist Wizard generates a list of steps for an imported image file, and tracks progress through those steps
• Cubic spline interpolation between graph points gives more accurate curves with fewer points
• Axes Checker briefly highlights the axes when they are defined or modified, to reveal entry mistakes
• Graph coordinates can be specified as date and time value, or as degrees, minutes and seconds
• Import by drag-and-drop
• Improved zooming, with a fill mode that allows keyboard-triggered zooming but rezooms when the application window is resized (a convenient alternative to window-in-window zooming)
• Color picking straight from the original image to filter an image and extract a specific curve
• Uploadable error report generated when an error is encountered, for effective error identification and repair
• Test suite for regression testing. This feature is for Engauge software developers.
• Replacement of Qt3 (which is at the end of its life) by Qt5. This feature is for Linux package maintainers.