I am thinking of the following:

Add checkbox "Append" (non-persistent setting, default off, put it where the "Clear clipboard" checkbox is and ~~drop that unnecessary functionality~~ move that functionality to wizard settings)
- This will only work for text-like formats (EDIT: and zip format), other formats will show an error messages with the option to replace or cancel
- In combination with batch mode
  - The filename field stays editable, and is not updated from the template when something new is copied
  - Instead, the text is appended into the same file on every copy
  - If something is copied which does not match the selected extension, it is ignored (preview is updated but nothing saved)
  - If the user selects an extension that does not support appending, show the above error messages
Context menu entry "Replace with clipboard content" becomes "Paste into file" with two sub-items: Replace and Append
- Replace is the existing functionality (no file-exists-warning, old file is moved to bin and can be restored with undo as usual)
- Append does what it says
- If append is selected, but it's not text-based, show error messages with the option to replace or cancel (same as above)
- Nice-to-have: SHIFT can be used to show the dialog (default is always to skip, independent of autosave setting)
- Nice-to-have: For some file formats known to not support appending stuff (e.g. PNG, JPG, ...) only show a top-level "Paste into file (replace)" entry (implemented with advanced query syntax)

Append into file #41

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