If I load a Word document into a JTextPane, is there a way I could drop a custom shape in it, then save it as a new Word document?
JTextPane
The results I\'m looking
You can try to extend the DocxEditorKit http://java-sl.com/docx_editor_kit.html adding your feature there
docx4all is a Swing-based docx editor.
Like DocxEditorKit, it is built on top of docx4j.
You'd need to extend it to support the functionality you are describing.