Hi Dimitri
I’ve been able to find the two stack traces that call preventDefault during a
mousemove event, they are:
anonymous(),
qx.event.type.Native.preventDefault,
qx.event.type.Roll.stop,
qx.ui.window.Window._onMoveRoll,
qx.ui.core.EventHandler._dispatchEvent,
qx.event.dispatch.AbstractBubbling.dispatchEvent,
qx.event.Manager.dispatchEvent,
qx.event.Registration.fireEvent,
qx.event.handler.Gesture._fireEvent,
qx.event.handler.GestureCore.prototype._fireRoll(),
qx.event.handler.GestureCore.prototype.gestureMove(),
qx.event.handler.GestureCore.prototype.checkAndFireGesture(),
qx.event.handler.Gesture.prototype.__ho(),
qx.event.handler.Gesture.prototype.checkAndFireGesture(),
anonymous(),
qx.event.dispatch.Direct.prototype.dispatchEvent(),
bP()
anonymous(),
qx.event.type.Native.preventDefault,
qx.ui.core.EventHandler._dispatchEvent,
qx.event.dispatch.AbstractBubbling.dispatchEvent,
qx.event.Manager.dispatchEvent,
qx.event.Registration.fireEvent,
qx.event.handler.Gesture._fireEvent,
qx.event.handler.GestureCore._fireRoll,
qx.event.handler.GestureCore.gestureMove,
qx.event.handler.GestureCore.prototype.checkAndFireGesture(),
qx.event.handler.Gesture.prototype.__ho(),
qx.event.handler.Gesture.prototype.checkAndFireGesture(),
anonymous(),
qx.event.dispatch.Direct.prototype.dispatchEvent(),
bP()
But it’s only the first stack trace that seems to trigger the problem; the
gesture code is trying to stop a “gesturemove” event but because the underlying
native event is a “mousemove”, it’s the mousemove which is actually getting
preventDefault’ed. To test whether this is a Qooxdoo bug or a Chrome bug, I
temporarily patched qx.event.type.Native.preventDefault to read:
/**
* Prevent browser default behavior, e.g. opening the context menu, ...
*/
preventDefault : function()
{
this.base(arguments);
if (this._native._original.type !== "mousemove")
qx.bom.Event.preventDefault(this._native);
},
Obviously far too crude a fix for real use but I think it shows that it’s not
some other part of Qooxdoo which is subsequently suppressing events because
only the browser is being excluded from preventDefault and the problem goes
away.
The solution may lie in qx.event.handler.GestureCore.gestureMove, lines 240
onward currently say:
if(!this.__isMultiPointerGesture) {
this.__fireTrack("track", domEvent, gesture.target);
this._fireRoll(domEvent, "touch", gesture.target);
}
I think that in order to provide a unified touch/pointer event system, the call
to this._fireRoll is trying to simulate a touch event (which would be
reasonable to want to preventDefault) but it’s associated with the mousemove
(domEvent is a “pointermove” event and domEvent._original is then “mousemove”
event), so I’ve tried patching it to this:
if(!this.__isMultiPointerGesture) {
if (domEvent._original && domEvent._original.type == "mousemove")
domEvent.preventDefault = function(){};
this.__fireTrack("track", domEvent, gesture.target);
this._fireRoll(domEvent, "touch", gesture.target);
}
That works, and as a workaround would be targeted at just this problem. I have
not tested it on any platforms which support gestures.
John
On 14/10/2015, 23:47, "Dimitri" <mi...@cargosoft.ru> wrote:
Hi,
We've recently hit a very nasty bug in our qooxdoo desktop app and
recent Chrome/Chromium versions. Symptoms are: if there is a selectable
text inside a qx.ui.window.Window, and you move the window (or just
single-click window header), you won't be able to select text by mouse
dragging anymore (double- or triple-clicking will work however). See a
link [1] to Playground snippet that demonstrates the issue. In case the
link expires, here is the code to run in Playground:
var win = new qx.ui.window.Window("First Window");
win.setWidth(300);
win.setHeight(200);
win.setShowMinimize(false);
this.getRoot().add(win, {left:20, top:20});
win.open();
var label = new qx.ui.basic.Label("Lorem ipsum dolor sit amet").set({
selectable: true
});
win.add(label);
Now the gory details. As I've already mentioned, the issue is observed
*only* in recent Chrome/Chromium releases, for all desktop platforms;
Firefox and older WebKit-based browsers, like Safari or GNOME Epiphany,
are not affected. Furthermore, we've been able to track this bug down to
particular changeset in Chrome's Blink engine [2]. We didn't bisect
further to determine particular commit, but it seems quite plausible
that the culprit is [3]:
Make the mousemove event cancellable
The mouse move event used to be non cancellable in the 90s and
when the specications changes in 2002-2003, not not everyone noticed.
The change was introduced about two years ago, in Chrome 31.0.1622.0.
Now guys, could you please help me understand what this issue is all
about? If my hypothesis is correct and it has something to do with
mousemove event cancellation, then what's going on? I could probably
suggest that mousemove events for the window, once canceled, are being
kept canceled forever? It's interesting that if you open DOM inspector
and just drag that label's DIV out of the window, somewhere to beginning
of BODY, you'll be able to select text again; that means, only the
window becomes "broken", not the entire application/document.
With all the above - is it a qooxdoo or a Chrome bug? If latter, we
should be able to concoct a plain non-qooxdoo MWE that Chrome guys would
probably expect from us. So here I'm kindly asking your assistance in
isolating (and, hopefully, fixing) this pesky bug.
Cheers,
Dimitri
[1] http://tinyurl.com/osswyny
[2]
http://build.chromium.org/f/chromium/perf/dashboard/ui/changelog_blink.html?url=/trunk&range=157209%3A157206
[3] http://src.chromium.org/viewvc/blink?view=rev&revision=157207
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