The current behavior for Homelink is to program the GPS coordinates to open the menu as you approach your door/gate. If the door/gate is in a multi-level garage like a condominium the menu pops up as you go up and down the ramps above the door/gate. With at least 4 satellites in view the altitude position can be determined. Saving this to the Homelink profile will remove these false menu popups.
Editor: Accuracy of GPS altitude is only specified as being +/- 75 ft 95% of the time (5% it could be far worse). It becomes even worse in a garage, where it’s likely the GPS signal will be completely lost. With a lot of clever programming, such as getting the barometric pressure for the local area via the 3G connection and having a calibrated pressure sensor on board, the altitude could be determined accurately. It would seem this features needs both software and additional hardware to be reasonably accurate.
Perhaps an alternate approach would be to leave the Homelink menu active for a wider distance range than is currently set, so it doesn’t pop up and close in this environment.