When talking about UI reform, the thing I hear most is that hard formatting needs to die and everyone needs to be forced to use styles. While I don’t think hard formatting should be abandoned completely, I do think that styles are an underused feature. And it’s underused because it’s a hassle to use. Creating styles is hard, editing styles is hard, and even applying styles takes a considerable while longer than simply hitting that “bold” button up at the top.
So here’s my attempt at making styles simpler. It’s a series of mockups for the tablet, but it would work the same way on the desktop.
The style list is drastically slimmed down. Only the first member of ordered groups of styles (like Headings) is shown until that member is used in the document — e.g. once you use “Heading 1”, the list will also show “Heading 2”, and once you use “Heading 2”, the list will also show “Heading 3”, etc. The list is also shorter because paragraph and character styles have separate drop-down menus.
Adding styles and editing them is done right within the menu — there’s a toolbar up at the top. Pushing edit shows all the included styles:
Within the style editing dialog, there’s a “Pin” button and a text box for a textual icon. When pinned, this icon ends up in the style bar, a toolbar for pinned styles that floats above a selection. It makes getting to commonly-used styles easy, easier than to Bold or Italic with a mouse, because a mouse has to cover less distance to reach these style buttons:
Looking forward to feedback. :~)
Click or Tap 
This gives the impression of a most useful feature, and so much easier to handle than the current style-editor.
There is one thing that misses clarity still, and that is the language choice.
It is a problem in practice, to explain to newcomers to LibreOffice how to set the language in a document.
Not fully illogical as a subset of signs, it is hard to find and very hard to set. That could be so much easier.
It often happens in countries like mine with large, different languages surrounding us, that multiple languages are needed within in one document, alternatingly.
.
When the interface for adjusting styles gets so logical and easy to use, please add the language feature on a clear place within this part of the UI too.
That does demand the possibility to rename styles, like header1.English, header1.German, header1.xxxx
This is a pretty good idea. I would hope, however, that this idea isn’t implemented at the expense of being able to dock the style list to the right or left of the document. There are times, especially when you’re working on a large document where styles are strictly enforced, when it’s a lot easier to place your cursor on the relevant part of the document simply click/double-click on the style already listed to the right — no need to click on the drop-down list, scroll, click, etc.
There’s one other thing to consider as well: keyboard access to styles.
One of the most useful features FrameMaker had (back when I used it regularly) was that if you pressed the F8 key,the style drop-down combobox (the “Paragraph” drop-down in your second screenshot) would clear and be replaced by a blinking cursor. You could immediately start typing the name of a style, and FrameMaker would attempt to fill in the rest by interpreting what style you were typing. Then when you were satisfied, you could press enter and a) the style would be applied to where your cursor had been, and b) your cursor would return to the main document.
This was especially useful if you created custom styles (or renamed existing styles) that you knew you would use a lot, i.e., you could have styles named
h1-heading 1
h2-heading 2
h3-heading 3
h4-heading 4
bt-body text
s1-subhead 1
bt-bullet text
nl-number list
p1-procedure 1
th-table header
tx-table text
etc.
This allowed you to apply a style by Pressing the F8, typing two letters, then pressing the Enter key. It was the kind of feature that you wouldn’t really think about under most circumstances, but I have missed it in every application I’ve used since.
LibreOffice ALMOST has that feature right now. However, the style list combobox in the button bar only has access to a limited subset of all the styles available in a document, so even if you go through all the trouble of modifying the styles to work as they do above, you can’t necessarily access them in the method I describe.