Very sluggish trackpad scrolling on Mac retina display with Qt5 but not Qt4?
I have an application that subclasses QScrollArea and scrolls a subclass of QWidget that does it's own painting. The widget content is complex (seismic data), but it scrolls fine with the trackpad on a retina Macbook pro when compiled in Qt4.8.5. Moving the code to Qt5.2.1 causes it to scroll VERY slowly.
I don't think this JUST due to 4x pixels… if I enable persistent scrollbars, and scroll by grabbing the scrollbars, the scrolling is a bit slower with 5.2.1 but still quite reasonable.
Are there other changes in trackpad behavior that are interfering here… I am assuming that kinetic scrolling isn't being somehow enabled? Anything else I should be looking at?
I would recommend bringing this question to the interest mailing. You'll find there Qt's developers/maintainers (this forum is more user oriented)