Aba show a warning if you searched for some pattern, switched to an external program and edited one of the found files, then switched back to Aba and pressed the Replace button. In this case, the search will be repeated to show you the changes you have made.
If you enter some frequent search pattern, you will get a plenty of matches, most of which will be useless for you.
For example, you want to search for the word
English in a large folder and type the first letter,
E. You will immediately get thousands of matches because the letter
E is the most frequent letter in English text. These matches may take gigabytes of memory and greatly slow down your computer. They are also useless, because you usually don't want to search for one letter in your files.
That is why Aba introduces a limit on the number of matches. By default, the limit is 1024 matches. If there are more matches in your files, the search will be paused until you click Search for more button. This simple measure limits the amount of RAM used by Aba and improves the performance of the program.
If you have enough amount of memory installed, you can increase the limit in the Options dialog.