Fix cb_view_adjustment_changed* callbacks issues

[JimnwQ]

Removes three FIXMEs in cb_view_adjustment_changed*:

• Fix stored_position hacks on cb_view_adjustment_value_changed
• Fix cb_view_adjustment_changed modifying the adjustment value

Closes:

• Scroll jumps back ~2 pages intermittently on Wayland (not on X11) #1028

The random scroll jumpings are occuring because GDK_SCROLL events are handled by GtkScrolledWindow internal scroll event listener, which sets adjustment values to it's private priv->unclamped_vadj_value + scroll_delta. As far as I can understand the girara session's GtkEventControllerScroll should handle all of them and no event should leak into GtkScrolledWindow's event controller, but it's still happening and I don't really know why.

To accommodate it, it's possible to allow both GtkScrolledWindow internal logic and installed mouse shortcuts to modify the adjustments. priv->unclamped_vadj_value and zathura->position_* should be set in adjustment value-changed signal callback, and refresh-view signal writes to the adjustment, so in theory everything is fine. The caveat is, GtkScrolledWindow's logic is bit weird and priv->unclamped_vadj_value is only set when the widget is not kinetic scrolling. And when the GDK_SCROLL event leaks, it starts kinetic scrolling hence never really sets priv->unclamped_vadj_value and just jumps to last place priv->unclamped_vadj_value is set to.

So the fix is simply cancelling kinetic scrolling whenever manually scrolling with position_set, sc_zoom so adjustment value-changed callback can correctly modify priv->unclamped_vadj_value.

This also restores the unintended feature of holding alt and scrolling allowing kinetic scrolling because ALT_MASK + GDK_SCROLL event handler is not installed, falling back to GtkScrolledWindow.

I thoroughly tested by pressing random keybindings on my machine, and so far didn't find any bug.

P.S. Thank you so much for creating such a great document viewer. Really been using zathura as the only document viewer forever.

Void Linux, Kernel 7.2.5, Sway (GDK_BACKEND=wayland)
GTK Version: 4.22.4
Girara Version: 2026.07.18

Edit: The only place where upper bound of adjustments is changed seem to be zooming, hence just restore the position ratio after setting the bounds on zoom.

[sebastinas]

It'd appreciate somebody with Wayland to test this PR.