heading value is presented between 0 and 360.
// string ApHeadingLabel( "Enter New Heading" );
// ApHeadingDialogMessage -> setLabel(ApHeadingLabel.c_str());
float heading = current_autopilot->get_DGTargetHeading();
+ while ( heading < 0.0 ) { heading += 360.0; }
ApHeadingDialogInput -> setValue ( heading );
ApHeadingDialogInput -> acceptInput();
FG_PUSH_PUI_DIALOG( ApHeadingDialog );