Alt-mousewheel scroll selection breaks transparency

[Kelvin Song]

After using Alt-mousewheel scroll selection, all objects with opacity values that were cycled through become 100% opaque. They go back to normal if you move them a little and refresh the display. In addition, when cycling, instead of temporarily multiplying the opacities of other objects in the way by 50%, it just sets the opacity to 50. This has the effect of making near-transparent objects appear more opaque, instead of less opaque.

I'm using Inkscape 0.48+devel r.

How to reproduce the bug

1 Open test file (or create your own with several overlapping objects with varying opacities)
2 Use Alt-Scroll selection to cycle through all the objects in the stack. The non-selected objects will all become 50% opaque, regardless of their opacity before.
3 Release the alt key. Every object will display as 100% opaque, even the ones that were originally semi-transparent.
4 If you interrupt the cycling (for example, by right clicking before releasing the alt key), all the objects will be stuck at 50% opacity.
5 Reset all the opacities back to normal by moving the objects.

[jazzynico (jazzynico)]

Confirmed on Debian testing, Inkscape trunk revision 12265.

[su_v (suv-lp)]

Duplicate of bug #1092374 “alt + scroll to select messes up opacity”?

[insaner (insaner)]

hey kelvin, please test the patch there, and if that works for you, can you mark as duplicate, and i will check in the changes

[Kelvin Song (kelvinsong)]

Sorry, I do not know how to test a patch, but if you're talking about trunk, it's still not fixed.

[insaner (insaner)]

hmm.. sorry about not answering, i thought launchpad would let me know automatically if someone replied.

to test a patch you can just download the patch to your inkscape src directory and run the command:

bzr patch bzrdiff-opacityfix-insaner2.diff

then compile, then test, and report back to us

[Kelvin Song (kelvinsong)]

I managed to compile and test—yes the patch fixes the bug !