Modal Dialogues cause a jump in page position

Open login page Scroll down the page a little Click on [?] help icon Confirm the page position doesn't jump to the top Login Open a course Turn editing on Open the activity chooser Confirm the page position doesn't jump to the top Navigate to the Profile Settings page Load the TinyMCE Image plugin and open the filepicker Confirm the page position doesn't jump to the top Chose wikimedia Search for some lolcats Select an image Confirm the page position doesn't jump to the top Close the dialogue Create a new Assignment, submit a PDF to it, and then go to grade it Open EditPDF Confirm the page position doesn't jump to the top Open the Comments Search Confirm the page position doesn't jump to the top Close it Chose the colour dropdown Confirm the page position doesn't jump to the top Navigate to the front page Open the JS console Run the following, and each time a dialogue appears, Confirm the page position doesn't jump to the top : d = new M.core.dialogue({}); // Test   d.destroy(); d = new M.core.confirm({}); // Test   d.destroy(); d = new M.core.ajaxException({}); // Test   d.destroy(); d = new M.core.exception({}); // Test   d.destroy(); d = new M.core.alert({});