When I try to apply a class (defined in a linked css file) to a selected portion of text through the drop-down menu, the class is applied at the "body" level of the document instead, thus modifying the whole page.
I'm not skilled enough in html / css to be sure that this behaviour is a bug. But when I manually write in the source code :
<div class="MyClass">Some text</div>
then it seems to work well. And even if it were not a bug, the French tooltip on the drop-down list would be misleading since it reads "Appliquer une classe à la sélection" (Apply a class to the selection).
I know it's not the place, but thank you for the editor :)
Okay, I now understand how it is supposed to work... It's not enough to just select the text : you have to make a block out of it (a paragraph block, for instance) and then apply the class to it. So I guess that the term "selection" in the tooltip refers to the current block and not the highlighted text.
Sorry for reporting this as a bug. I'll have to test and tweak more next time. Thanks again for making Kompozer.