diff --git a/README.md b/README.md
index 86a83fa7..4b615c8e 100644
--- a/README.md
+++ b/README.md
@@ -16,7 +16,10 @@ This README is being written.<br>
 
 ## Updates
 
-*Note that today's entry may be updated later today Eastern Time.*
+*Note that today's entry (Eastern Time) may be updated later today.*
+
+* **16 June 2016**
+	* Added `uiWindowContentSize()`, `uiWindowSetContentSize()`, and `uiWindowOnContentSizeChanged()` methods for manipulating uiWindow content sizes. Note the use of "content size"; the size you work with does NOT include window decorations (titlebars, menus, etc.).
 
 * **15 June 2016**
 	* Added `uiFormDelete()`; thanks to @emersion.
diff --git a/darwin/window.m b/darwin/window.m
index 7cab10b4..03c86ac1 100644
--- a/darwin/window.m
+++ b/darwin/window.m
@@ -12,6 +12,9 @@ struct uiWindow {
 	void (*onPositionChanged)(uiWindow *, void *);
 	void *onPositionChangedData;
 	BOOL suppressPositionChanged;
+	void (*onContentSizeChanged)(uiWindow *, void *);
+	void *onContentSizeChangedData;
+	BOOL suppressSizeChanged;
 };
 
 @interface windowDelegateClass : NSObject<NSWindowDelegate> {
@@ -19,6 +22,7 @@ struct uiWindow {
 }
 - (BOOL)windowShouldClose:(id)sender;
 - (void)windowDidMove:(NSNotification *)note;
+- (void)windowDidResize:(NSNotification *)note;
 - (void)registerWindow:(uiWindow *)w;
 - (void)unregisterWindow:(uiWindow *)w;
 - (uiWindow *)lookupWindow:(NSWindow *)w;
@@ -61,6 +65,15 @@ struct uiWindow {
 		(*(w->onPositionChanged))(w, w->onPositionChangedData);
 }
 
+- (void)windowDidResize:(NSNotification *)note
+{
+	uiWindow *w;
+
+	w = [self lookupWindow:((NSWindow *) [note object])];
+	if (!w->suppressSizeChanged)
+		(*(w->onContentSizeChanged))(w, w->onContentSizeChangedData);
+}
+
 - (void)registerWindow:(uiWindow *)w
 {
 	mapSet(self->windows, w->window, w);
@@ -250,7 +263,9 @@ void uiWindowSetPosition(uiWindow *w, int x, int y)
 
 void uiWindowCenter(uiWindow *w)
 {
+	w->suppressPositionChanged = YES;
 	[w->window center];
+	w->suppressPositionChanged = NO;
 }
 
 void uiWindowOnPositionChanged(uiWindow *w, void (*f)(uiWindow *, void *), void *data)
@@ -259,6 +274,28 @@ void uiWindowOnPositionChanged(uiWindow *w, void (*f)(uiWindow *, void *), void
 	w->onPositionChangedData = data;
 }
 
+void uiWindowContentSize(uiWindow *w, int *width, int *height)
+{
+	NSRect r;
+
+	r = [w->window contentRectForFrameRect:[w->window frame]];
+	*width = r.size.width;
+	*height = r.size.height;
+}
+
+void uiWindowSetContentSize(uiWindow *w, int width, int height)
+{
+	w->suppressSizeChanged = YES;
+	[w->window setContentSize:NSMakeSize(width, height)];
+	w->suppressSizeChanged = NO;
+}
+
+void uiWindowOnContentSizeChanged(uiWindow *w, void (*f)(uiWindow *, void *), void *data)
+{
+	w->onContentSizeChanged = f;
+	w->onContentSizeChangedData = data;
+}
+
 void uiWindowOnClosing(uiWindow *w, int (*f)(uiWindow *, void *), void *data)
 {
 	w->onClosing = f;
@@ -300,7 +337,7 @@ static int defaultOnClosing(uiWindow *w, void *data)
 	return 0;
 }
 
-static void defaultOnPositionChanged(uiWindow *w, void *data)
+static void defaultOnPositionContentSizeChanged(uiWindow *w, void *data)
 {
 	// do nothing
 }
@@ -329,7 +366,8 @@ uiWindow *uiNewWindow(const char *title, int width, int height, int hasMenubar)
 	}
 	[windowDelegate registerWindow:w];
 	uiWindowOnClosing(w, defaultOnClosing, NULL);
-	uiWindowOnPositionChanged(w, defaultOnPositionChanged, NULL);
+	uiWindowOnPositionChanged(w, defaultOnPositionContentSizeChanged, NULL);
+	uiWindowOnContentSizeChanged(w, defaultOnPositionContentSizeChanged, NULL);
 
 	return w;
 }
diff --git a/doc/windowmovesize b/doc/windowmovesize
new file mode 100644
index 00000000..ec8bd966
--- /dev/null
+++ b/doc/windowmovesize
@@ -0,0 +1,3 @@
+you should never need to use these functions
+they are provided only for the cases when ABSOLUTELY NECESSARY
+the operating system may ignore your requests, for instance, if you are giving it invalid numbers or a size too small to fit; this is all system-defined