[SINCE Orbeon Forms 2017.2]
The toolbox shows familiar undo and redo icons.
When hovering over the icons, a tooltip tells you which operation is undone or redone.
You can undo most operations which change important aspects of the form:
insertion and deletion
control, grid, grid row, section and section template
control (via drag and drop)
section (up/down/right/left arrows)
rename control, grid or section
other control, grid or section settings, including itemsets, labels, hint, and validations
section template merging (new in 2017.2)
In this initial version, it is not yet possible to undo changes to the form definition's source code with Edit Source, or changes to actions, services, and other global form settings. We hope to support undoing these operations in the future.
Blog post: New Orbeon Forms 2017.2 feature: undo and redo