## Summary of the Pull Request
**Naive implementation** of exporting the text buffer of the current pane
into a text file triggered from the tab context menu.
**Disclaimer: this is not an export of the command history,**
but rather just a text buffer dumped into a file when asked explicitly.
## References
Should provide partial solution for #642.
## Detailed Description of the Pull Request / Additional comments
The logic is following:
* Open a file save picker
* The location is Downloads folder (should be always accessible)
* The suggest name of the file equals to the pane's title
* The allowed file formats list contains .txt only
* If no file selected stop
* Lock terminal
* Read all lines till the cursor
* Format each line by removing trailing white-spaces and adding CRLF if not wrapped
* Asynchronously write to selected file
* Show confirmation
As the action is relatively fast didn't add a progress bar or any other UX.
As the buffer is relatively small, holding it entirely in the memory rather than
writing line by line to disk.
c089ae0c57