Open a bullet list style
Select "Position -> Number followed by"
3 options available:
The enhancement is to add a non-breaking space ( ) to the list above.
On exporting to XHTML, the spaces and tabs are not rendered and the text is not fasten from the bullet.
For numbering lists, there is provision to add characters following the numbering, and one can add a non-breaking space by pasting it in the field. This feature is not available in bullet lists.
ODF has only the values "listtab", "nothing" and "space"(=U+0020) in the text:label-followed-by attribute (19.833 ODF 1.3 part3). I would not change that.
Instead, the attributes style:num-prefix (19.506) and style:num-suffix (19.507) are explicitly allowed in combination with text:bullet-char. It is only LibreOffice, that does not support it. So I would go to implement the "before" and "after" fields known from numbering, for bullets too.
I think export to XHTML is a different problem, because XHTML has no tab stops anyway and a tab-character is a white-space as others. A tab after a bullet is mostly used to jump to the indent position. To get such behavior in XHTML, you need "tab-size" from CSS3.
Thank you Regina for the comments.
You suggestion to implement "before" and "after" bullet character fits as well.
Changing bug summary to reflect correct approach.
"the attributes style:num-prefix (19.506) and style:num-suffix (19.507) are explicitly allowed in combination with text:bullet-char. It is only LibreOffice, that does not support it. So I would go to implement the "before" and "after" fields known from numbering, for bullets too."
Next step is to get a proposal for a to be changed UI. (Perhaps together with a proposal for a UI for the new feature to allow texts other than dot between the levels of a numbered list.)