The border of the ContentControl is displayed abnormally when the paragraph's TextAlignment is set to Center or Right.
Austria (German) region is set in windows. Digit grouping symbol is set "," and decimal symbol is ".".
Inserting rounded rectangle shape in RichTextBox produces broken geometry like so:
The non-breaking space breaks the word if a number character is presented in the word. For example, the following text should be treated as one word - 10,0 % but it is separated into to words - 10,0 and %.
The issue can be observed when the word should break on the next line.