Wt

Animation with WStackedWidget using the Fade effect shows visual glitches under Firefox/gecko. Also, if animations queue, it is possible to enter a state where no content is displayed for the WStackedWidget.

This was tested using the latest github version of Wt (3.3.1-30-g813a601), but I believe the problems may be present in 3.3.1, as well. Browsers tested include: Debian Wheezy/iceweasel 17.0.10, Debian Wheezy/Chromium 31.0.1650.63, Windows 7/Firefox 27.0, Windows 7/Chrome 32.0.1700.107 m, Windows 7/IE 11.0.9600.16476, update versions 11.0.2.

I've attached a test program to drive the issue. The test program performs animated transitions every 2 seconds, with an initial duration of 50ms. This can be changed to 1000ms and 3000ms using pushbuttons. At 1000ms, glitchy transitions should be noticeable in Firefox/gecko browsers. With a 3000ms transition, the animations continue for a short time before fading out completely --- in all browsers tested. This is clearly a somewhat unrealistic torture test, but I have seen similar occurrences with an application that uses a 500ms animation on a WStackedWidget triggered by user action.

I've also attached a patch (see notes on patch) that seems to help with these issues in limited testing.