Apparently, putting the disabling method call between disconnectSignals()/connectSignals() was not enough, because closing the Location window also caused the name to reset to "New Location" - apparently closing the window while the focus is in the spin box also triggers an AngleSpinBox::valueChanged() signal. Someone has to look into the code of AngleSpinBox.
For this case, I solved this with putting the focus on the location search box after "Use as default" is disabled.
Apparently, putting the disabling method call between disconnectSigna ls()/connectSig nals() was not enough, because closing the Location window also caused the name to reset to "New Location" - apparently closing the window while the focus is in the spin box also triggers an AngleSpinBox: :valueChanged( ) signal. Someone has to look into the code of AngleSpinBox.
For this case, I solved this with putting the focus on the location search box after "Use as default" is disabled.