New blog post: http://blog.tempel.org/2015/10/SearchingMultipleXojoProjects.html
Another way [to search inside your project(s)] is to print as pdf (OS X, Windows, Linux: status unknown, read * below) your project(s).
OS X:
You already have a virtual printer to pdf built-in, so just print your projects,
Windows:
Download and install a free (or not) virtual pdf printer and print your project to pdf,
Linux:
Same as Windows IF there is a virtual pdf printer available. *
To print the whole project to pdf, be sure to have set the focus to the navigatior AND no entry selected, then print to pdf.
AND you can print only parts of the project: select an entry to print in the navigation pane and print it.
Also, if you want graphics (your windows) inside the pdf, go to the Xojo IDE preferences, and set the correct value to get that.
Nota: I do not know the status of 2015r3 in this domain (if it have been improved for example).
Of course, there is no Table of Contents, but you can add one if you want: Preview from OS X is able to add pages to a pdf, many other free or paying tools exists that allow you to do that. Even Adobe have an Acrobat development environment ! (search hard in their web to reach it).
Con
You have to make a print here and then
Pro
If (like me) you have to rely on it, you will be really happy to have it handly.
I had the luck to have a recent print of a lost project: this allowed me to re-create it from a three month ago old project.
Last:
The generated pdf is not perfect / recreating a current project from an old and the last generated pdf is not so easy, but this is by far better than relying on memory (especially when your memory is not reliable).
I always was dubitative on the use of this feature until I needed it and was able to use it ! Thanks a lot Xojo !