Fix panel dragging on Linux Aura

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc

Index: ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
index e3f1179c97597cb63622c8583613ac72b87bebb7..385a51768f7081d7daabce59155a24d8e5c97ba4 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
@@ -944,6 +944,7 @@ void DesktopWindowTreeHostX11::InitX11Window(
   if (swa.override_redirect)
     attribute_mask |= CWOverrideRedirect;
 
+  x_bounds_ = params.bounds;
   bounds_ = params.bounds;
   xwindow_ = XCreateWindow(
       xdisplay_, x_root_window_,
@@ -1120,6 +1121,14 @@ void DesktopWindowTreeHostX11::OnCaptureReleased() {
 }
 
 void DesktopWindowTreeHostX11::DispatchMouseEvent(ui::MouseEvent* event) {
+  // The event location is relative to |x_bounds_|. However, Aura uses |bounds_|
+  // for all computations, including converting to screen coordinates. Offset
+  // the event location so that converting the event location to screen
+  // coordinates returns the correct value.
+  gfx::Vector2d event_offset(x_bounds_.origin() - bounds_.origin());
+  event->set_location(event->location() + event_offset);
+  event->set_root_location(event->location() + event_offset);
+

[sadrul, 2014/03/13 15:41:31]

This doesn't look right. Can you update
DesktopWindowTreeHostX11::GetClientAreaBoundsInScreen() instead to return
x_bounds_?

[pkotwicz, 2014/03/13 19:47:48]

I think I understand what you are asking.
You are hoping that we will be able to return a correct position in the event
window and a correct position in screen coordinates.

Personally I prefer my solution over yours.

A couple comments about your solution:
- We really should not be highjacking
DesktopWindowTreeHostX11::GetClientAreaBoundsInScreen() to return the real
window bounds. Retrieving |x_bounds_| is not the same as calling GetClientRect()
http://msdn.microsoft.com/en-us/library/aa932115.aspx
- |x_bounds_| should only have the real origin of the window (not its real
size). I foresee a plethora of theoretical problems with the local size being
different from the size in screen coordinates.

I think that it is ok for the position of the mouse event in the coordinates of
the event window to be off while the window is being moved. Do you foresee any
problems with this being the case?

   if (!g_current_capture || g_current_capture == this) {
     SendEventToProcessor(event);
   } else {
@@ -1339,6 +1348,7 @@ uint32_t DesktopWindowTreeHostX11::Dispatch(const base::NativeEvent& event) {
       bool size_changed = bounds_.size() != bounds.size();
       bool origin_changed = bounds_.origin() != bounds.origin();
       previous_bounds_ = bounds_;
+      x_bounds_ = bounds;
       bounds_ = bounds;
       if (size_changed)
         OnHostResized(bounds.size());