Aghhh. Please please could the IDE have the search do all the tabs. PLEASE PLEASE
I am not an expert but I think there is not an option to do it. Probably you can use another editor I recommend you Notepad++
I know that for sure but that's why I put this message in the Development forum - the forum where they ask for IDE modifications in the hope that they might add such a simple (well maybe it isn't) addition to the IDE.
Editor doe not depends on the Arduino IDE but on the Processing IDE.
As often in open source you can re use other soft to avoid to reinvent everything.
It is often very difficult to change external software.
The best solution is to use external editor.
I recommend you Notepad++
Notepad++ is very limited ! It works only on Windows