--- a/widget/headless/HeadlessWidget.cpp
+++ b/widget/headless/HeadlessWidget.cpp
@@ -9,16 +9,33 @@
 #include "BasicEvents.h"
 #include "MouseEvents.h"
 #include "mozilla/gfx/gfxVars.h"
 #include "mozilla/ClearOnShutdown.h"
 
 using namespace mozilla::gfx;
 using namespace mozilla::layers;
 
+using mozilla::LogLevel;
+
+#ifdef MOZ_LOGGING
+
+#include "mozilla/Logging.h"
+static mozilla::LazyLogModule sWidgetLog("Widget");
+static mozilla::LazyLogModule sWidgetFocusLog("WidgetFocus");
+#define LOG(args) MOZ_LOG(sWidgetLog, mozilla::LogLevel::Debug, args)
+#define LOGFOCUS(args) MOZ_LOG(sWidgetFocusLog, mozilla::LogLevel::Debug, args)
+
+#else
+
+#define LOG(args)
+#define LOGFOCUS(args)
+
+#endif /* MOZ_LOGGING */
+
 /*static*/ already_AddRefed<nsIWidget>
 nsIWidget::CreateHeadlessWidget()
 {
   nsCOMPtr<nsIWidget> widget = new mozilla::widget::HeadlessWidget();
   return widget.forget();
 }
 
 namespace mozilla {
@@ -66,25 +83,28 @@ HeadlessWidget::HeadlessWidget()
   if (!sActiveWindows) {
     sActiveWindows = new nsTArray<HeadlessWidget*>();
     ClearOnShutdown(&sActiveWindows);
   }
 }
 
 HeadlessWidget::~HeadlessWidget()
 {
+  LOG(("HeadlessWidget::~HeadlessWidget() [%p]\n", (void *)this));
+
   Destroy();
 }
 
 void
 HeadlessWidget::Destroy()
 {
   if (mDestroyed) {
     return;
   }
+  LOG(("HeadlessWidget::Destroy [%p]\n", (void *)this));
   mDestroyed = true;
 
   if (sActiveWindows) {
     int32_t index = sActiveWindows->IndexOf(this);
     if (index != -1) {
       RefPtr<HeadlessWidget> activeWindow = GetActiveWindow();
       sActiveWindows->RemoveElementAt(index);
       // If this is the currently active widget and there's a previously active
@@ -184,16 +204,18 @@ HeadlessWidget::RaiseWindow()
     mWidgetListener->WindowActivated();
 }
 
 void
 HeadlessWidget::Show(bool aState)
 {
   mVisible = aState;
 
+  LOG(("HeadlessWidget::Show [%p] state %d\n", (void *)this, aState));
+
   // Top-level window and dialogs are activated/raised when shown.
   if (aState && (mTopLevel == this || mWindowType == eWindowType_dialog)) {
     RaiseWindow();
   }
 
   ApplySizeModeSideEffects();
 }
 
@@ -201,16 +223,18 @@ bool
 HeadlessWidget::IsVisible() const
 {
   return mVisible;
 }
 
 nsresult
 HeadlessWidget::SetFocus(bool aRaise)
 {
+  LOGFOCUS(("  SetFocus %d [%p]\n", aRaise, (void *)this));
+
   // aRaise == true means we request activation of our toplevel window.
   if (aRaise) {
     HeadlessWidget* topLevel = (HeadlessWidget*) GetTopLevelWidget();
 
     // The toplevel only becomes active if it's currently visible; otherwise, it
     // will be activated anyway when it's shown.
     if (topLevel->IsVisible())
       topLevel->RaiseWindow();
@@ -228,16 +252,19 @@ bool
 HeadlessWidget::IsEnabled() const
 {
   return mEnabled;
 }
 
 void
 HeadlessWidget::Move(double aX, double aY)
 {
+  LOG(("HeadlessWidget::Move [%p] %f %f\n", (void *)this,
+       aX, aY));
+
   double scale = BoundsUseDesktopPixels() ? GetDesktopToDeviceScale().scale : 1.0;
   int32_t x = NSToIntRound(aX * scale);
   int32_t y = NSToIntRound(aY * scale);
 
   if (mWindowType == eWindowType_toplevel ||
       mWindowType == eWindowType_dialog) {
       SetSizeMode(nsSizeMode_Normal);
   }
@@ -313,16 +340,18 @@ HeadlessWidget::Resize(double aX,
     NotifyWindowMoved(aX, aY);
   }
   return Resize(aWidth, aHeight, aRepaint);
 }
 
 void
 HeadlessWidget::SetSizeMode(nsSizeMode aMode)
 {
+  LOG(("HeadlessWidget::SetSizeMode [%p] %d\n", (void *)this, aMode));
+
   if (aMode == mSizeMode) {
     return;
   }
 
   nsBaseWidget::SetSizeMode(aMode);
 
   // Normally in real widget backends a window event would be triggered that
   // would cause the window manager to handle resizing the window. In headless