Hi Sowmya,
The Matrix uses /dev/input/touchscreen0 as input. Please check the /etc/init.d/matrix-gui-2.0 file for configuration.
I'm not able to help you with details, but as far as I know a daemon is running in the background and it reads the touch events. Then, based on the knowledge about the icons position in the HTML5 browser, it launches the corresponding application. Please check these files where this is done:
<sdk_dir>/example-applications/matrix-gui-2.0/submenu.php - calling run_script.php when an application is detected
<sdk_dir>/example-applications/matrix-gui-2.0/run_script.php - executing the application using execute_command.sh, located in the same folder
Best regards,
Miroslav