E-book viewer: scrolling to the previous section doesn't always work in Flow mode

[etc205]

1. Open the Quick Start Guide that comes with calibre in E-book viewer.
2. Right-click to display the viewer controls.
3. Click on "Preferences -> Page layout -> Flow mode", then "OK" to enable Flow mode.
4. Right-click to hide the controls.
5. Press Ctrl+t to display the table of contents.
6. Expand the ToC to show "Common Tasks -> Task 2: Conversion -> 2.4 Auto Conversion" and click on "2.4 Auto Conversion". The viewer jumps to the beginning of the corresponding chapter in the guide, see the attached image.
7. Press Ctrl+PageUp to scroll the the previous section. The viewer jumps to the beginning of "2.3: Conversion basics".

Press Ctrl+PageUp again. The viewer doesn't jump the the beginning of "2.2: Why are there different e-book formats?".

Also, this is probably not relevant and is just a typo, but the name of the ToC item at step 6 should be "2.4: Auto Conversion", i.e. a colon is missing.

Calibre version: 5.16,
OS: Windows 10 Home 1803.

[Kovid Goyal (kovid)]

Fixed in branch master. The fix will be in the next release. calibre is usually released every alternate Friday.

 status fixreleased