PanMouseWheelTool issues
lazarus / 55-TAChart

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wp · 2012-09-04 19:58

The attached demo uses two mousewheel tools for panning:
ChartToolset1PanMouseWheelToolHor - pans horizontally by rotating the
mouse wheel and holding ALT down
ChartToolset1PanMouseWheelToolVert - pans vertically by rotating the
mouse wheel and holding SHIFT down
Run the program. Pan vertically, then horizontally - everything works
fine. But when you pan vertically a second time, the chart does not
change any more. You have to use the horizontal pan again to get back
the vertical pan effect.

It just looks as if a "Handled" or something is missing for the
horizontal pan. Or maybe I a doing something wrong...

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Ask · 2012-09-05 03:09

It seems to be a LCL/widgetset issue:
http://bugs.freepascal.org/view.php?id=22800
(note "Steps to reproduce" section).

Meanwhile, you can use Ctrl modifier instead of Alt.

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wp · 2012-09-05 10:44

Thank you for your efforts.

The reason why I selected the ALT key is because of its location on
the keyboard: if you consider the CTRL key which is at the very left-
bottom edge as the origin of a coordinate system, then the SHIFT key
which is above CTRL points along the y direction, and the ALT key
which is to the right of CTRL points along the x direction. Therefore
I tend to assign the SHIFT key to tools acting vertically, and the ALT
key to tools acting horizontally. In this way I try to memorize the
various key combinations.