Ctrl+wheel zooming (was: font size in "documentation" tool view)

[René J.V. Bertin]

Hi,

Since Ctrl+MouseWheel zooming came up, here's a gripe I have with that feature.

Scroll wheel events are also generated when using a trackpad's 2-finger scroll (and presumably, hscroll and vscroll borders). If inertial scrolling is used/enabled/provided you get scroll wheel events during coasting, i.e. when the user is no longer scrolling actively ... and they may keep coming in when visible scrolling has stopped already. It happens often to me that I scrolled a bit of code and then want to use a keyboard shortcut, and that my text starts zooming instead. Even with a shortcut to get back to 100% that is quite annoying - enough that Qt actually has some filters in place to prevent it from happening on OS X, and that some applications (like Konsole) make the feature optional.

I've done some preliminary work together with Thomas Lübking last year, to add a form of hysteresis to the event handling which prevents zooming when the Ctrl key is pressed while scroll events are still coming in. Worked quite nicely but we never got around to submitting it to Qt, for some reason.

Before anyone suggests it: I find inertial scrolling very useful when you don't have something like a trackball with actual inertia, and a large screen (or long documents). I wouldn't want to have to chose between it and scroll-wheel zooming; I'd rather lose the latter (and just use Ctrl-+ and Ctrl--). KDE4 had a global setting for that, which sadly didn't make it into KF5.

R.