I've never used TextPad so I can't compare UEStudio with it. However, there are some things you can do with the output captured in the output window:
(a) if you have an error message, and the text has something which looks like a line number in it, double-clicking the line will usually take you to the place in your source code which generated the error;
(b) you can copy either the selected line or the entire output to the clipboard. Unfortunately, there seems to be no option to copy only part of a line which is selected. But send an e-mail to IDM at firstname.lastname@example.org
and propose that as a feature suggestion. I'm sure it must be easy enough to implement.
If you copy the line from output to the clipboard and paste it into a new message, then select just the word(s) you need, you could then do a "find in files" from the "Search" menu.