Optimizely's Interactive Mode is designed to allow you to modify your website while it is loaded in the Editor. For instance, you would use Interactive Mode to edit hover states, an item on a drop-down menu or within a tray.
Clicking an element in the editor normally brings up the contextual menu, which means you are not able to actually interact with dynamic elements. Enter Interactive Mode to interact with your page as you normally would in the browser. Get it to the state that you want to modify it in and then click Editing Mode or hit Ctrl+I on your keyboard.
Interactive Mode will always show you the original page so that you can interact with it. Changing back to Editing Mode will show you the page in that state with the variation code applied.