Auto-separation: Do not allow enabling if unbunching is present

Check for scheduled dispatch/unbunching in enable command
Show in button tooltip

src/timetable_cmd.cpp

@@ -667,6 +667,8 @@ CommandCost CmdTimetableSeparation(TileIndex tile, DoCommandFlag flags, uint32_t
 	CommandCost ret = CheckOwnership(v->owner);
 	if (ret.Failed()) return ret;
 
+	if (HasBit(p2, 0) && (HasBit(v->vehicle_flags, VF_SCHEDULED_DISPATCH) || v->HasUnbunchingOrder())) return CommandCost(STR_ERROR_SEPARATION_MUTUALLY_EXCLUSIVE);
+
 	if (flags & DC_EXEC) {
 		for (Vehicle *v2 = v->FirstShared(); v2 != nullptr; v2 = v2->NextShared()) {
 			if (HasBit(p2, 0)) {

src/timetable_gui.cpp

@@ -568,7 +568,7 @@ struct TimetableWindow : GeneralVehicleWindow {
 			this->SetWidgetDisabledState(WID_VT_START_DATE, v->orders == nullptr || HasBit(v->vehicle_flags, VF_TIMETABLE_SEPARATION) || HasBit(v->vehicle_flags, VF_SCHEDULED_DISPATCH));
 			this->SetWidgetDisabledState(WID_VT_RESET_LATENESS, v->orders == nullptr);
 			this->SetWidgetDisabledState(WID_VT_AUTOFILL, v->orders == nullptr || HasBit(v->vehicle_flags, VF_AUTOMATE_TIMETABLE));
-			this->SetWidgetDisabledState(WID_VT_AUTO_SEPARATION, HasBit(v->vehicle_flags, VF_SCHEDULED_DISPATCH));
+			this->SetWidgetDisabledState(WID_VT_AUTO_SEPARATION, HasBit(v->vehicle_flags, VF_SCHEDULED_DISPATCH) || v->HasUnbunchingOrder());
 			this->EnableWidget(WID_VT_AUTOMATE);
 			this->EnableWidget(WID_VT_ADD_VEH_GROUP);
 			this->SetWidgetDisabledState(WID_VT_LOCK_ORDER_TIME, !wait_lockable);
@@ -643,6 +643,21 @@ struct TimetableWindow : GeneralVehicleWindow {
 				}
 				return false;
 			}
+			case WID_VT_AUTO_SEPARATION: {
+				if (HasBit(this->vehicle->vehicle_flags, VF_SCHEDULED_DISPATCH)) {
+					SetDParam(0, STR_TIMETABLE_AUTO_SEPARATION_TOOLTIP);
+					SetDParam(1, STR_CANNOT_ENABLE_BECAUSE_SCHED_DISPATCH);
+					GuiShowTooltips(this, STR_TOOLTIP_SEPARATION_CANNOT_ENABLE, close_cond, 2);
+				} else if (this->vehicle->HasUnbunchingOrder()) {
+					SetDParam(0, STR_TIMETABLE_AUTO_SEPARATION_TOOLTIP);
+					SetDParam(1, STR_CANNOT_ENABLE_BECAUSE_UNBUNCHING);
+					GuiShowTooltips(this, STR_TOOLTIP_SEPARATION_CANNOT_ENABLE, close_cond, 2);
+				} else {
+					GuiShowTooltips(this, STR_TIMETABLE_AUTO_SEPARATION_TOOLTIP, close_cond);
+				}
+				return true;
+			}
+
 			default:
 				return false;
 		}
@@ -1206,7 +1221,7 @@ static constexpr NWidgetPart _nested_timetable_widgets[] = {
 			EndContainer(),
 			NWidget(NWID_VERTICAL, NC_EQUALSIZE),
 				NWidget(WWT_PUSHTXTBTN, COLOUR_GREY, WID_VT_AUTOMATE), SetResize(1, 0), SetFill(1, 1), SetDataTip(STR_TIMETABLE_AUTOMATE, STR_TIMETABLE_AUTOMATE_TOOLTIP),
-				NWidget(WWT_PUSHTXTBTN, COLOUR_GREY, WID_VT_AUTO_SEPARATION), SetResize(1, 0), SetFill(1, 1), SetDataTip(STR_TIMETABLE_AUTO_SEPARATION, STR_TIMETABLE_AUTO_SEPARATION_TOOLTIP),
+				NWidget(WWT_PUSHTXTBTN, COLOUR_GREY, WID_VT_AUTO_SEPARATION), SetResize(1, 0), SetFill(1, 1), SetDataTip(STR_TIMETABLE_AUTO_SEPARATION, STR_NULL),
 				NWidget(WWT_DROPDOWN, COLOUR_GREY, WID_VT_EXTRA), SetResize(1, 0), SetFill(1, 1), SetDataTip(STR_TIMETABLE_EXTRA_DROP_DOWN, STR_TIMETABLE_EXTRA_DROP_DOWN_TOOLTIP),
 			EndContainer(),
 			NWidget(NWID_VERTICAL, NC_EQUALSIZE),