Oracle SQL Developer by default automatically opens the object editor when you click on an object in your connection tree or schema browser. For most folks this is very convenient. But if you are selecting objects to drag them to a model or to the worksheet, this can get annoying as the focus of the screen changes when you don’t want it to.
The other scenario this feature might disrupt more than delight is when you want to click around the database in the tree and every time you click on an object, the object editor automatically changes to the selected object.
You can disable this automatic browsing behavior in SQL Developer by modifying this preference:
Tools > Preferences > Database > ObjectViewer > Open Object on Single Click
OK, I do realize my description of the problem may have confused the heck out of you just now. So instead of more words, how about a couple of animations of the object-click behavior with the option ON and OFF?