DEC VT220 Terminal Emulation Support

Epic's EHR "Text" application utilizes DEC VT220 terminal emulation. We are currently using RDM embedded PuTTY sessions for management, but would prefer to switch to the RDM native SSHShell terminal. In order for this to be feasible, we need the terminal's VT220 support improved, specifically:

- DEC VT220 terminal emulation support
- Support control codes:

• Locked scrolling regions (used a lot)
• Terminal resizing (80/132 column – DECCOLM)
• Origin mode (DECOM)
• Cursor movement
• Character attributes (bold, inverse, underline, DECDWL/DECDHL)
• DEC special graphics / VT100 line drawing character set

I should note that enabling the "use legacy terminal" option does improve certain workflows, but not everything. If helpful, we can perform testing of the Epic applications and any RDM changes and provide feedback.