(This is a split-off of part of bug 154756) The Page pane of the Page Style dialog has a mock preview of the effect of the current settings, including an illustration of the progression of a few glyphs of text. Unfortunately, the preview does not properly regard both the vertical progression direction and the glyph orientation. You see, when using vertical text progression, Western-language-group glyphs may be rotated by 90-degrees (so that their baseline is a vertical line on the page), or stacked on top of each other (i.e. not sharing a baseline). The current default is rotation. The preview, however, shows the example stacked. The preview should take all settings (on this pane and elsewhere), figure out both the progression and the orientation angle, and lay out the preview glyphs accordingly.
Created attachment 189945 [details] Page style dialog with incorrect preview + suggested correction Screenshot of page style dialog with top-to-bottom, left-to-right mode chose, but with the English sample glyphs stacked instead of rotated - even though when you choose these settings, English gets rotated. In red, i've sketched what the preview should be showing, more or less.
The preview string must contain a character from CJK and a latin character at the same time. Otherwise the writing modes "sideways-rl" and "tb-rl" cannot be distinguished. The request for a better preview is valid.
(In reply to Regina Henschel from comment #2) > The preview string must contain a character from CJK and a latin character > at the same time. Otherwise the writing modes "sideways-rl" and "tb-rl" > cannot be distinguished. Yes, I agree that would be even better. A few things to remember, though: * Adding more glyphs makes the preview smaller (or would require showing a multi-line preview, which is more complex). * People who don't know CJK scripts well enough may not be able to distinguish between different orientations of CJK glyphs; so, hopefully, the chosen glyphs should be such for which this is as straightforward as possible to notice.