The threshold for system basic timers has changed on windows

This breaks the animations in main window because dragging a dock widget
when it is undocked creates another event loop and the Qt events are not
processed any more.

Reviewed-by: Trust Me

2 files changed, 7 insertions, 3 deletions

diff --git a/src/corelib/animation/qabstractanimation.cpp b/src/corelib/animation/qabstractanimation.cpp
index 6bbd801..2769040 100644
--- a/src/corelib/animation/qabstractanimation.cpp
+++ b/src/corelib/animation/qabstractanimation.cpp
@@ -162,9 +162,9 @@
     //on windows if you're currently dragging a widget an inner eventloop was started by the system
     //to make sure that this timer is getting fired, we need to make sure to use the system timers
     //that will send a WM_TIMER event. We do that by settings the timer interval to 11
-    //It is 11 because QEventDispatcherWin32Private::registerTimer specifically checks if the interval
-    //is greater than 10 to determine if it should use a system timer (or the multimedia timer).
-#define STARTSTOP_TIMER_DELAY 11
+    //It is 16 because QEventDispatcherWin32Private::registerTimer specifically checks if the interval
+    //is greater than 11 to determine if it should use a system timer (or the multimedia timer).
+#define STARTSTOP_TIMER_DELAY 16
 #else
 #define STARTSTOP_TIMER_DELAY 0
 #endif
diff --git a/src/corelib/kernel/qeventdispatcher_win.cpp b/src/corelib/kernel/qeventdispatcher_win.cpp
index aae351c..1e6402f 100644
--- a/src/corelib/kernel/qeventdispatcher_win.cpp
+++ b/src/corelib/kernel/qeventdispatcher_win.cpp
@@ -539,6 +539,10 @@ void QEventDispatcherWin32Private::registerTimer(WinTimerInfo *t)
 
     int ok = 0;
 
+    //in the animation api, we delay the start of the animation
+    //for the dock widgets, we need to use a system timer because dragging a native window
+    //makes Windows start its own event loop.
+    //So if this threshold changes, please change STARTSTOP_TIMER_DELAY in qabstractanimation.cpp accordingly.
     if (t->interval > 15 || !t->interval || !qtimeSetEvent) {
         ok = 1;
         if (!t->interval)  // optimization for single-shot-zero-timer