Comment 4 for bug 240185

This patch has a little bug in goto_line method in Search module.

I liked so much the real time verification of line number.

Two things that you need do fix are:
 * Negative numbers must be invalid numbers.
 * If you put a character in entry, this line:

gotoline = int(self.entry.get_text())

returns a error. Catch the exception and change the entry background to red.