Reduce the fullscreen window height by 1px on activation loss.

ui/views/win/hwnd_message_handler.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/win/hwnd_message_handler.h"
 
 #include <dwmapi.h>
 #include <oleacc.h>
 #include <shellapi.h>
 #include <tchar.h>
@@ skipping 315 matching lines @@
       is_first_nccalc_(true),
       menu_depth_(0),
       id_generator_(0),
       needs_scroll_styles_(false),
       in_size_loop_(false),
       touch_down_contexts_(0),
       last_mouse_hwheel_time_(0),
       dwm_transition_desired_(false),
       sent_window_size_changing_(false),
       left_button_down_on_caption_(false),
+      background_fullscreen_hack_(false),
       autohide_factory_(this),
       weak_factory_(this) {}
 
 HWNDMessageHandler::~HWNDMessageHandler() {
   delegate_ = NULL;
   // Prevent calls back into this class via WNDPROC now that we've been
   // destroyed.
   ClearUserData();
 }
 
@@ skipping 184 matching lines @@
     SetWindowLong(hwnd(), GWL_STYLE, style & ~WS_MAXIMIZE);
 
   gfx::Size old_size = GetClientAreaBounds().size();
   SetWindowPos(hwnd(), NULL, bounds_in_pixels.x(), bounds_in_pixels.y(),
                bounds_in_pixels.width(), bounds_in_pixels.height(),
                SWP_NOACTIVATE | SWP_NOZORDER);
 
   // If HWND size is not changed, we will not receive standard size change
   // notifications. If |force_size_changed| is |true|, we should pretend size is
   // changed.
-  if (old_size == bounds_in_pixels.size() && force_size_changed) {
+  if (old_size == bounds_in_pixels.size() && force_size_changed &&
+      !background_fullscreen_hack()) {

[sky, 2016/02/19 22:30:50]

Shouldn't SetBounds() reset background_fullscreen_hack_? The SetBounds() called
from PostPorcessActivateMessage shouldn't tell the delegate, but the if someone
else calls SetBounds (it's public) then I would expect it to reset
background_fullscreen_hack_.

[ananta, 2016/02/19 23:21:26]

Done. Added a SetBoundsInternal private function which is called from
PostProcessActivateMessage and from SetBounds. We reset the flag in the public
function.

     delegate_->HandleClientSizeChanged(GetClientAreaBounds().size());
     ResetWindowRegion(false, true);
   }
 
   if (direct_manipulation_helper_)
     direct_manipulation_helper_->SetBounds(bounds_in_pixels);
 }
 
 void HWNDMessageHandler::SetSize(const gfx::Size& size) {
   SetWindowPos(hwnd(), NULL, 0, 0, size.width(), size.height(),
@@ skipping 286 matching lines @@
   }
   if (!app_icon.isNull()) {
     base::win::ScopedHICON previous_icon = app_icon_.Pass();
     app_icon_ = IconUtil::CreateHICONFromSkBitmap(*app_icon.bitmap()).Pass();
     SendMessage(hwnd(), WM_SETICON, ICON_BIG,
                 reinterpret_cast<LPARAM>(app_icon_.get()));
   }
 }
 
 void HWNDMessageHandler::SetFullscreen(bool fullscreen) {
+  set_background_fullscreen_hack(false);
   fullscreen_handler()->SetFullscreen(fullscreen);
   // If we are out of fullscreen and there was a pending DWM transition for the
   // window, then go ahead and do it now.
   if (!fullscreen && dwm_transition_desired_)
     PerformDwmTransition();
 }
 
 void HWNDMessageHandler::SizeConstraintsChanged() {
   LONG style = GetWindowLong(hwnd(), GWL_STYLE);
   // Ignore if this is not a standard window.
@@ skipping 65 matching lines @@
       return result;
   }
 
   if (delegate_) {
     delegate_->PostHandleMSG(message, w_param, l_param);
     if (message == WM_NCDESTROY)
       delegate_->HandleDestroyed();
   }
 
   if (message == WM_ACTIVATE && IsTopLevelWindow(window))
-    PostProcessActivateMessage(LOWORD(w_param), !!HIWORD(w_param));
+    PostProcessActivateMessage(LOWORD(w_param), !!HIWORD(w_param),
+                               reinterpret_cast<HWND>(l_param));
   return result;
 }
 
 LRESULT HWNDMessageHandler::HandleMouseMessage(unsigned int message,
                                                WPARAM w_param,
                                                LPARAM l_param,
                                                bool* handled) {
   // Don't track forwarded mouse messages. We expect the caller to track the
   // mouse.
   base::WeakPtr<HWNDMessageHandler> ref(weak_factory_.GetWeakPtr());
@@ skipping 77 matching lines @@
 }
 
 void HWNDMessageHandler::SetInitialFocus() {
   if (!(GetWindowLong(hwnd(), GWL_EXSTYLE) & WS_EX_TRANSPARENT) &&
       !(GetWindowLong(hwnd(), GWL_EXSTYLE) & WS_EX_NOACTIVATE)) {
     // The window does not get keyboard messages unless we focus it.
     SetFocus(hwnd());
   }
 }
 
-void HWNDMessageHandler::PostProcessActivateMessage(int activation_state,
-                                                    bool minimized) {
+void HWNDMessageHandler::PostProcessActivateMessage(
+    int activation_state,
+    bool minimized,
+    HWND window_gaining_or_losing_activation) {
   DCHECK(IsTopLevelWindow(hwnd()));
   const bool active = activation_state != WA_INACTIVE && !minimized;
   if (delegate_->CanActivate())
     delegate_->HandleActivationChanged(active);
+
+  if (!::IsWindow(window_gaining_or_losing_activation))
+    window_gaining_or_losing_activation = ::GetForegroundWindow();
+
+  // If the window losing activation is a fullscreen window, we reduce the size
+  // of the window by 1px. i.e. Not fullscreen. This is to work around an
+  // apparent bug in the Windows taskbar where in it tracks fullscreen state on
+  // a per thread basis. This causes it not be a topmost window when any
+  // maximized window on a thread which has a fullscreen window is active. This
+  // affects the way these windows interact with the taskbar, they obscure it
+  // when maximized, autohide does not work correctly, etc.
+  // By reducing the size of the fullscreen window by 1px, we ensure that the
+  // taskbar no longer treats the window and in turn the thread as a fullscreen
+  // thread. This in turn ensures that maximized windows on the same thread
+  /// don't obscure the taskbar, etc.
+  if (!active) {
+    if (fullscreen_handler_->fullscreen() &&
+        ::IsWindow(window_gaining_or_losing_activation)) {
+      // Reduce the bounds of the window by 1px to ensure that Windows does
+      // not treat this like a fullscreen window.
+      MONITORINFO monitor_info = {sizeof(monitor_info)};
+      GetMonitorInfo(MonitorFromWindow(hwnd(), MONITOR_DEFAULTTOPRIMARY),
+                      &monitor_info);
+      gfx::Rect shrunk_rect(monitor_info.rcMonitor);
+      shrunk_rect.set_height(shrunk_rect.height() - 1);
+      set_background_fullscreen_hack(true);
+      SetBounds(shrunk_rect, false);
+    }
+  } else if (background_fullscreen_hack()) {
+    // Restore the bounds of the window to fullscreen.
+    DCHECK(fullscreen_handler_->fullscreen());
+    set_background_fullscreen_hack(false);
+    MONITORINFO monitor_info = {sizeof(monitor_info)};
+    GetMonitorInfo(MonitorFromWindow(hwnd(), MONITOR_DEFAULTTOPRIMARY),
+                   &monitor_info);
+    SetBounds(gfx::Rect(monitor_info.rcMonitor), false);
+  }
+
 }
 
 void HWNDMessageHandler::RestoreEnabledIfNecessary() {
   if (delegate_->IsModal() && !restored_enabled_) {
     restored_enabled_ = true;
     // If we were run modally, we need to undo the disabled-ness we inflicted on
     // the owner's parent hierarchy.
     HWND start = ::GetWindow(hwnd(), GW_OWNER);
     while (start) {
       ::EnableWindow(start, TRUE);
@@ skipping 25 matching lines @@
     tme.hwndTrack = hwnd();
     tme.dwHoverTime = 0;
     TrackMouseEvent(&tme);
   } else if (mouse_tracking_flags != active_mouse_tracking_flags_) {
     TrackMouseEvents(active_mouse_tracking_flags_ | TME_CANCEL);
     TrackMouseEvents(mouse_tracking_flags);
   }
 }
 
 void HWNDMessageHandler::ClientAreaSizeChanged() {
+  // Ignore size changes due to fullscreen windows losing activation.
+  if (background_fullscreen_hack())
+    return;
   gfx::Size s = GetClientAreaBounds().size();
   delegate_->HandleClientSizeChanged(s);
 }
 
 bool HWNDMessageHandler::GetClientAreaInsets(gfx::Insets* insets) const {
   if (delegate_->GetClientAreaInsets(insets))
     return true;
   DCHECK(insets->IsEmpty());
 
   // Returning false causes the default handling in OnNCCalcSize() to
@@ skipping 1069 matching lines @@
   } else if (!GetParent(hwnd())) {
     RECT window_rect;
     HMONITOR monitor;
     gfx::Rect monitor_rect, work_area;
     if (GetWindowRect(hwnd(), &window_rect) &&
         GetMonitorAndRects(window_rect, &monitor, &monitor_rect, &work_area)) {
       bool work_area_changed = (monitor_rect == last_monitor_rect_) &&
                                (work_area != last_work_area_);
       if (monitor && (monitor == last_monitor_) &&
           ((fullscreen_handler_->fullscreen() &&
-            !fullscreen_handler_->metro_snap()) ||
+            !fullscreen_handler_->metro_snap() &&
+            !background_fullscreen_hack()) ||

[sky, 2016/02/19 22:30:50]

Shouldn't this reset background_fullscreen_hack_ if the size is changing in some
other way?

[ananta, 2016/02/19 23:21:26]

Done. We reset the flag if it is true and the bounds don't differ by 1px.

             work_area_changed)) {
         // A rect for the monitor we're on changed.  Normally Windows notifies
         // us about this (and thus we're reaching here due to the SetWindowPos()
         // call in OnSettingChange() above), but with some software (e.g.
         // nVidia's nView desktop manager) the work area can change asynchronous
         // to any notification, and we're just sent a SetWindowPos() call with a
         // new (frequently incorrect) position/size.  In either case, the best
         // response is to throw away the existing position/size information in
         // |window_pos| and recalculate it based on the new work rect.
         gfx::Rect new_window_rect;
@@ skipping 389 matching lines @@
 
     default:
       left_button_down_on_caption_ = false;
       break;
   }
   return handled;
 }
 
 
 }  // namespace views