Encountered in Ubuntu 13.04 and Mint 15.
Steps to reproduce:
Method A:
1. gksu synaptic
2. Turn off "Settings -> Preferences -> General -> Show package properties in the main window" if it was on (or else you won't get a lot of warnings in stderr).
3. Click on package list and start browsing it with Up and Down keys. You may also use the mouse, but it will take more time.
Additional info:
The big load of messages thrown to stderr is described here: https://bugs.launchpad.net/ubuntu/+source/synaptic/+bug/1135687
The freeze itself is reported here: https://bugs.launchpad.net/ubuntu/+source/synaptic/+bug/1178024
Method B:
1. Download the archive from the attachment and unpack it.
2. Install g++ and libgtkmm-3.0-dev
3. g++ main.cc helloworld.cc -o test `pkg-config gtkmm-3.0 --cflags --libs`
4. chmod +x test
5. gksu ./test
6. Start clicking on the button (or pressing Enter)
Additional info:
The source code was taken from gtkmm examples: https://git.gnome.org/browse/gtkmm-documentation/tree/examples/book/helloworld
HelloWorld::on_button_clicked() function was modified to print 20 pretty long messages to stderr (to simulate what happens to Synaptic in Method A). You can set this count higher or lower.
With messages number set to 20 there's an interesting side effect: shortly before freeze, one of these messages gets actually printed to the console instead of being buffered until the app termination.
Status changed to 'Confirmed' because the bug affects multiple users.