I've been having some small problems running remote apps on my local display. I login to remote servers using ssh -X and can fire up X applications with no problems. The problem comes when interacting with the application. For example, I opened up a file using emacs on the remote machine and I can scroll through the text with the arrow keys just fine, but as soon as I try using the shortcuts, such as CTL-v, emacs quits with the error

X protocol error: BadAccess (attempt to access private resource denied) on protocol request 102
or
X protocol error: BadWindow (invalid Window parameter) on protocol request 38

Those are the usual errors I encounter. The only other error messages I receive differ by request number. These problems occur on all remote machines that I access, and it is not specific to emacs. I just recently upgraded to Slack 10 and I did not encounter this error in 9.1.

I have tried several things such as enabling X11Forwarding in /etc/ssh/ssh_config and I have also added the remote machines to xhost. Any suggestions?

I found the solution to my problem. All I had to do was to add
ForwardX11Trusted yes
to my ssh_config.

you can also do ssh -Y instead of ssh -X to fix this problem