Do you mean the editor window doesn't have the focus, or BLIde itself doesn't have the focus?
Blide Itself. Sometimes if I'm compiling a very large project which is forcing several modules to rebuild, I hit compile and click into another window to answer an IM or something, and then Blide can't throw an error window up because it doesn't have the focus. I know I shouldn't be so impatient really, but I just thought I'd mention it on the offchance that it could be fixed.