Added BWindow::ResizeToPreferred().

* B_AUTO_UPDATE_SIZE_LIMITS only really makes sense for resizable
  windows, and it only sets the minimum/maximum window size.
* ResizeToPreferred() resizes the window to its preferred size, and
  also supports height-for-width layouts.

headers/os/interface/Window.h

@@ -165,6 +165,7 @@ public:
 			void				MoveTo(float x, float y);
 			void				ResizeBy(float dx, float dy);
 			void				ResizeTo(float width, float height);
+			void				ResizeToPreferred();
 
 			void				CenterIn(const BRect& rect);
 			void				CenterOnScreen();

src/kits/interface/Window.cpp

@@ -2521,7 +2521,26 @@ BWindow::ResizeTo(float width, float height)
 }
 
 
-// Center the window in the passed in rect.
+void
+BWindow::ResizeToPreferred()
+{
+	Layout(false);
+
+	float width = fTopView->PreferredSize().width;
+	width = std::min(width, fTopView->MaxSize().width);
+	width = std::max(width, fTopView->MinSize().width);
+
+	float height = fTopView->PreferredSize().height;
+	height = std::min(width, fTopView->MaxSize().height);
+	height = std::max(width, fTopView->MinSize().height);
+
+	if (GetLayout()->HasHeightForWidth())
+		GetLayout()->GetHeightForWidth(width, NULL, NULL, &height);
+
+	ResizeTo(width, height);
+}
+
+
 void
 BWindow::CenterIn(const BRect& rect)
 {
@@ -2534,7 +2553,6 @@ BWindow::CenterIn(const BRect& rect)
 }
 
 
-// Centers the window on the screen the window is currently on.
 void
 BWindow::CenterOnScreen()
 {