Bug 407449

Created attachment 119997 [details]
Horizontal scroll bar appears although page is narrower than viewport

SUMMARY
When the shown page (or all visible pages) is narrower than the viewport, the horizontal scroll bar is not needed. *1 But if there are any other pages which are wider than the viewport, the horizontal scroll bars appears also for the narrower pages. Toggling Continuous mode has no effect.

STEPS TO REPRODUCE
1. Open a TI datasheet (they have rotated pages): e. g. http://www.ti.com/lit/gpn/DRV8343-Q1
2. Choose Fit Width --> no horizontal scrollbar
3. Toggle Continuous --> observe: All pages are scaled to same width
4. Zoom out a very little bit (middle mouse button + drag) --> observe: pages are not scaled to same width anymore.

OBSERVED RESULT
Horizontal scroll bar appears, although page is already narrower than the viewport.

EXPECTED RESULT
Horizontal scroll bar appears only if the page is wider than the viewport.

If Continuous is enabled, horizontal scroll bars make sense to move the landscape orientated pages horizontally. But if Continuous is disabled, the horizontal scroll bar does not make much sense for the portrait pages.

When the horizontal scroll bar appears, it is not possible to advance to the next page with the right arrow key. In case of TI datasheets, which have only one or two landscape pages at the end, navigating with left/right arrow keys is convenient. (Even more as soon as Bug 169614 is fixed.) Of couse, clicking the Previous/Next Page buttons still works.

Can the horizontal scroll bar / horizontal scrolling funtionality be disabled if all shown pages are narrower than the viewport?

*1) It is possible to move the landscape pages by dragging a portrait page out of the viewport, but is this really needed?

SOFTWARE/OS VERSIONS
KDE Neon 5.15
KDE Plasma Version: 5.15.5
KDE Frameworks Version: 5.57.0
Qt Version: 5.12.0
Okular 1.7.0