Created attachment 149921 [details]
Sample HTML file that replicates the defect
I have attached a sample page that demonstrates this issue. On the sample page, click anywhere within the page to see the alert box appear after a delay. Remove the style attribute on the body tag and refresh the page, notice that clicking now causes the alert box to appear almost instantaneously.
This problem is reproducable in both Safari 5.1.7 and Chrome 19.0.1084.56 m
Created attachment 186211 [details]
Another web page test case
This test case tests dragging large numbers of objects around on screen*. To start, simply click the text/grey area and drag. If you hold CTRL when clicking on the text/grey area, webkitUserSelect will be set to 'none', otherwise it will be set to 'auto'.
Note that I am currently running in Chrome, and that the result I'm seeing is that the performance while dragging is significantly reduced when webkitUserSelect is set to 'none'.
* The particular project I am working on currently requires large numbers of DOM elements (and I'd like to have the text not get selected :) ).
Could you post the latter test case as a HTML document on Bugzilla? We need a BSD licensed reduction. Also, on Mac, control+click appears to cause WebKit to show context menu so that's not convenient for me. Could you make it so that it always reproduces?
Created attachment 186422 [details]
Second Test Case Version 2 (repro case always happens)
Here is a second revision of the second test case. This test case tests dragging large numbers of objects around on screen*. To start, simply click the text/grey area and drag; webkitUserSelect is always set to 'none', so the bug should reproduce all the time.