This is an advanced task.

Please fix the following issues:

- Saving a GroundOverlay from Edit Maps and loading it via the open button in the Edit Maps doesn't display the ground overlay. However loading it via "File->Open" works as intended.

- Adding a Polygon via the "Add Polygon" button and then adding nodes leads to crashes on some installs. Please investigate this bug and fix it.

- Fix visibility of the balloon in case pause is pressed while watching a tour: If a tour contains balloons and the pause button is clicked while watching the tour then the any balloons that are supposed to pop up after pressing pause just don't appear at all.