On a site I'm building, a user can edit certain fields on a node that cause a chain reaction to happen (which I've implemented using
hook_nodeapi() and its "update" operation).
Since this chain reaction potentially affects a lot of other content, I'd like to inform the user of exactly what other content will be changed, which depends on the changed field values, unknow until the user submits the node. After the user has read the list of affected content, I'd like to give them the option to click on Yes, which will save the node and start the chain reaction, or click No, which will take them back to the node edit form (with edits intact).
How can I make a confirmation form appear after the user clicks on Save?