Open Radar

 
Summary:

It is no longer possible to manually start GUI programs with another User account.
Fast user switching is fine for switching between accounts for separate humans, however,
it is also valuable to be able to run processes under different accounts, all managed by a single person.
For example, I have a "git" user and several other accounts running daemons so that I can share
data with friends and colleagues. I manage these accounts via the Terminal & shell from my normal user account. This means that I can reference my personal data (e.g.: email descriptions of problem reports and notes that I've kept from previous actions) while simultaneously working on the other account.

Steps to Reproduce:

Start Terminal.app
Switch to another user on the local machine
Start any GUI application

e.g.:

% su - {user}
% open /Applications/Automator.app

Expected Results:

The application should appear on the screen.

Actual Results:

% open /Applications/Automator.app
LSOpenURLsWithRole() failed with error -10810 for the file /Applications/Automator.app

% open /Applications/Vim.app
Sun Feb 28 16:15:55 hymie Vim[1240] <Error>: kCGErrorFailure: Set a breakpoint @ CGErrorBreakpoint() to catch errors as they are logged.
_RegisterApplication(), FAILED TO establish the default connection to the WindowServer, _CGSDefaultConnection() is NULL.

Regression:

This works perfectly until at least OS X 10.5.8

Notes: