Is it possible to implement a popup dialog when a content author approves a Bundle Workflow i.e. in Activity dashboard in Tridion, when a content author selects a particular Next Activity in the dropdown, we want to show a popup with a message like “By approving this bundle, I certify that I have obtained all the necessary approvals for the content changes from the requestors .Etc. etc….”. This should happen only on selection of particular next Activity.
This can be solved using a UI extension. In short, you can target the Activity dialogue from JQuery and make manipulate the DOM which opens up for a variety of approaches.
The simplest, imho, would be to initially hide the "Finish Activity" button and display a fake "Finish Activity" button to display a modal dialogue with your approval message. If the users clicks "Yes" you can then display the correct "Finish Activity" button and let them finish their Activity.