Pressing Cancel when prompted to save a file before building does not cancel the build

In the Build and Run options, enable "Save all files before build", "Always build project before deploying it", and "Always deploy project before running it".

Steps to reproduce:
1. Make a change to a read-only file.
2. Press Ctrl + B to build, or Ctrl + R to run the project.
3. You are prompted for how to save the file, press Cancel.
PROBLEM: The project is still built and ran.

This feature was added in (I think) 2.2, but no longer works in 2.4.