This is the text box line editor.

Use the arrow keys to move the cursor, and CTRL+Left/Right or ALT+Left/Right to move by word. CTRL+Home/End moves to the start/end.

Type to edit the lines.

The special codes listed at the bottom of the screen can be used to embed variable words/numbers into the text.
The ${B#} codes for buttons on a gamepad or keyboard, such as ESC or (X), are defined in General Game Settings->Platform-specific Options->Button Strings for Textboxes.

Embed codes also in map names, battle captions, menu item names (including the in-battle hero menus), and the script commands for expanding embed codes. They don't work in text slices yet :(

Press CTRL+SPACE to choose special characters to insert at the current cursor location.

CTRL+C Copies the current line.

CTRL+V Pastes the previously copied line, replacing the line that the cursor is on.

CTRL+BACKSPACE or ALT+BACKSPACE deletes the previous word, and CTRL+DELETE or ALT+DELETE deletes the next word.