If you are using CQ5.x you will notice that there is a confirmation dialog for deleting/deactivating pages in the WCM console. No such confirmation dialog is presented when you activate a page. In some projects it may be a requirement to present such a confirmation dialog for activation also.
You will have to overlay:
Create the same folder structure in apps and then copy the SiteAdmin.Actions.js node from libs to the same folder in apps. This will ensure the jcr:content node under the JS file is also copied.
Then edit the SiteAdmin.Actions.js from apps. You should replace the CQ.wcm.SiteAdmin.activatePage function with the lines (435-520) from this SiteAdmin.Actions.js file.
Ideally you should not not completely overlay the siteadmin.Actions.js as you might run into problems when a SP brings a new SiteAdmin.Actions.js with it. Instead just overlay the function you want to change. Use the clientlib approach and create a new JS file, attach it to the same clientlib as the SiteAdmin.Actions.js and redefine the function you want to change in that new JS file.