There are several issues with Find/Replace on the Linux version. The first is as in the title. If you search a document for a string, if you click the Find button twice quickly (double click I guess) then it jumps an extra entry.
So say there are 10 matches. You search and the first gets highlighted. Click Find and the second gets highlighted. If you click again quickly, instead of the third one being highlighted, it jumps to the 4th. If you keep clicking quickly it jumps 2 at a time. Same happens for Replace - of course this means more things get replaced than you expect!
Next issue: select some text and hit Ctrl+H for replace. If you tab into the replace field, some times (or most of the time) any text in the replace field is not highlighted. And usually when you've put the text in, the text in the document is not highlighted any more. (Seems like text can't be highlighted in the document and find dialog at the same time.) So you try to replace something and the button basically does nothing because nothing is highlighted.