Show confirmation window before clearing/removing dispatch schedule

src/lang/english.txt

@@ -7153,6 +7153,12 @@ STR_SCHDISPATCH_ADD_DEPARTURE_SLOTS_START                       :{BLACK}Start:
 STR_SCHDISPATCH_ADD_DEPARTURE_SLOTS_STEP                        :{BLACK}Period:
 STR_SCHDISPATCH_ADD_DEPARTURE_SLOTS_END                         :{BLACK}End:
 
+STR_SCHDISPATCH_QUERY_CLEAR_SCHEDULE_CAPTION                    :{WHITE}Clear Departure Slots
+STR_SCHDISPATCH_QUERY_CLEAR_SCHEDULE_TEXT                       :{WHITE}Are you sure you want to clear all {NUM} departure slot{P "" s} from this schedule?
+
+STR_SCHDISPATCH_QUERY_REMOVE_SCHEDULE_CAPTION                   :{WHITE}Delete Schedule
+STR_SCHDISPATCH_QUERY_REMOVE_SCHEDULE_TEXT                      :{WHITE}Are you sure you want to delete this schedule (containing  {NUM} departure slot{P "" s})?
+
 STR_ERROR_SCHDISPATCH_TRIED_TO_ADD_TOO_MANY_SLOTS               :{WHITE}Tried to add too many departure slots at once
 
 # Modifier key toggle window

src/schdispatch_gui.cpp

@@ -729,6 +729,26 @@ struct SchdispatchWindow : Window {
 		this->SetDirty();
 	}
 
+	static void ClearScheduleCallback(Window *win, bool confirmed)
+	{
+		if (confirmed) {
+			SchdispatchWindow *w = (SchdispatchWindow*)win;
+			if (w->IsScheduleSelected()) {
+				DoCommandP(0, w->vehicle->index | (w->schedule_index << 20), 0, CMD_SCHEDULED_DISPATCH_CLEAR | CMD_MSG(STR_ERROR_CAN_T_TIMETABLE_VEHICLE));
+			}
+		}
+	}
+
+	static void RemoveScheduleCallback(Window *win, bool confirmed)
+	{
+		if (confirmed) {
+			SchdispatchWindow *w = (SchdispatchWindow*)win;
+			if (w->IsScheduleSelected()) {
+				DoCommandP(0, w->vehicle->index | (w->schedule_index << 20), 0, CMD_SCHEDULED_DISPATCH_REMOVE_SCHEDULE | CMD_MSG(STR_ERROR_CAN_T_TIMETABLE_VEHICLE));
+			}
+		}
+	}
+
 	void OnDropdownSelect(int widget, int index) override
 	{
 		switch (widget) {
@@ -740,11 +760,15 @@ struct SchdispatchWindow : Window {
 						break;
 
 					case SCH_MD_CLEAR_SCHEDULE:
-						DoCommandP(0, this->vehicle->index | (this->schedule_index << 20), 0, CMD_SCHEDULED_DISPATCH_CLEAR | CMD_MSG(STR_ERROR_CAN_T_TIMETABLE_VEHICLE));
+						if (this->GetSelectedSchedule().GetScheduledDispatch().empty()) return;
+						SetDParam(0, (uint)this->GetSelectedSchedule().GetScheduledDispatch().size());
+						ShowQuery(STR_SCHDISPATCH_QUERY_CLEAR_SCHEDULE_CAPTION, STR_SCHDISPATCH_QUERY_CLEAR_SCHEDULE_TEXT, this, ClearScheduleCallback);
+
 						break;
 
 					case SCH_MD_REMOVE_SCHEDULE:
-						DoCommandP(0, this->vehicle->index | (this->schedule_index << 20), 0, CMD_SCHEDULED_DISPATCH_REMOVE_SCHEDULE | CMD_MSG(STR_ERROR_CAN_T_TIMETABLE_VEHICLE));
+						SetDParam(0, (uint)this->GetSelectedSchedule().GetScheduledDispatch().size());
+						ShowQuery(STR_SCHDISPATCH_QUERY_REMOVE_SCHEDULE_CAPTION, STR_SCHDISPATCH_QUERY_REMOVE_SCHEDULE_TEXT, this, RemoveScheduleCallback);
 						break;
 				}
 			}