In order to make screen and gnome-terminal communicate with each other, we first decided to change the screen program’s code to expose a library interface. However since:
1) screen’s code is old fashioned. i.e. it has many global variables which is not desirable for a shared library and
2) screen and g-t are under different licenses.
It is not feasible to make the screen program as a shared library object.
Thus we decided to have a third program as the messenger between g-t and screen. ”Pipes” (or file descriptors) are going to be used to read/write commands from/to screen.
The flow would be:
When g-t is loaded, it will create an instance of screen with the pipe fd as its parameter. Screen would be modified so that each time a command is written to the pipe, it would react properly.Each terminal would have one instance of the screen fd. Each screen fd can have multiple sub-screens.
To make the pipe bidirectional we actually need two file descriptors:·
screen –> g-t for:
o Scroll back buffer contents,
o Copy,
o Get current screens,·
g-t –> screen for:
o Create a new screen,
o Switch screen,
o Search,
o Paste,
o Show tab for current screens
Notes:
Semaphores will be used to prevent deadlock.
A protocol is also needed to make the communication happen.One endpoint of a pipe will write a command to it, the command will be read and interpreted by the other endpoint and proper reaction would be performed.
Protocol initial design:·
:newScreen options (readonly/writeonly) \r\n·
:switchTo screenID \r\n·
:copy numberOfChars \r\n data data ….data \r\n·
:paste numberOfChars \r\n data data … data \r\n·
:find searchLiteral \r\n·
:getScreens \r\n·
:showTab screen1 options \r\n screen2 options \r\n …
(To send commands to screen ‘-X’ option can be used.)
). This is a very simple illustration of this part of my project without menus of course, but helps me to go through screen code without worrying about integration with g-t. (Coding didn’t take more than half an hour actually but digging screen code to find where everything is took more time). For adding menus I plan to look at GTK library and gnome-terminal code. 
then we make it as a shared library object and it will expose a library interfaces to be called in vte/g-t. 