Copies the properties of this editor into an existing editor.
Each snip in this editor is copied and inserted into dest. In addition, this editor's filename, maximum undo history setting, keymap, interactive caret threshold, and overwrte-styles-on-load settings are installed into dest. This editor's style list is copied and the copy is installed as the style list for dest.
This editor's dragability, selection visiblity state, and scroll step are installed into dest.