(svn r17922) -Fix [FS#3291]: crash when closing NewGRF parameter window with no NewGRF selected

src/newgrf_gui.cpp

@@ -749,6 +749,7 @@ struct NewGRFWindow : public Window {
 				this->sel = newsel;
 				this->preset = -1;
 				this->InvalidateData();
+				this->DeleteChildWindows(WC_QUERY_STRING); // Remove the parameter query window
 				break;
 			}
 
@@ -791,6 +792,8 @@ struct NewGRFWindow : public Window {
 				uint i = (pt.y - this->GetWidget<NWidgetBase>(SNGRFS_FILE_LIST)->pos_y) / this->resize.step_height + this->vscroll.GetPosition();
 
 				for (c = this->list; c != NULL && i > 0; c = c->next, i--) {}
+
+				if (this->sel != c) this->DeleteChildWindows(WC_QUERY_STRING); // Remove the parameter query window
 				this->sel = c;
 
 				this->InvalidateData();

src/window.cpp

@@ -645,12 +645,14 @@ void Window::ReInit()
 
 /** Find the Window whose parent pointer points to this window
  * @param w parent Window to find child of
- * @return a Window pointer that is the child of w, or NULL otherwise */
-static Window *FindChildWindow(const Window *w)
+ * @param wc Window class of the window to remove; WC_INVALID if class does not matter
+ * @return a Window pointer that is the child of w, or NULL otherwise
+ */
+static Window *FindChildWindow(const Window *w, WindowClass wc)
 {
 	Window *v;
 	FOR_ALL_WINDOWS_FROM_BACK(v) {
-		if (v->parent == w) return v;
+		if ((wc == WC_INVALID || wc == v->window_class) && v->parent == w) return v;
 	}
 
 	return NULL;
@@ -658,13 +660,14 @@ static Window *FindChildWindow(const Window *w)
 
 /**
  * Delete all children a window might have in a head-recursive manner
+ * @param wc Window class of the window to remove; WC_INVALID if class does not matter
  */
-void Window::DeleteChildWindows() const
+void Window::DeleteChildWindows(WindowClass wc) const
 {
-	Window *child = FindChildWindow(this);
+	Window *child = FindChildWindow(this, wc);
 	while (child != NULL) {
 		delete child;
-		child = FindChildWindow(this);
+		child = FindChildWindow(this, wc);
 	}
 }
 

src/window_gui.h

@@ -621,7 +621,7 @@ public:
 	void DrawViewport() const;
 	void DrawSortButtonState(int widget, SortButtonState state) const;
 
-	void DeleteChildWindows() const;
+	void DeleteChildWindows(WindowClass wc = WC_INVALID) const;
 
 	void SetDirty() const;
 	void ReInit();