Wt

When pending events are queued on the browser (due to communication or server delay, etc.), they are processed in a batch on the server and this can lead to display problems --- under some circumstances. This report describes one way this can happen (using github version 3.3.0-7-g53cd144), along with a test program and some captured communication output. The issue is not believed to be browser-specific, although it does require javascript.

The attached test program (tabwidget_bug_20130417a.cc) displays a TabWidget with three tabs. To drive the problem:

1. Run the program on a server and navigate to the application page in a browser.
2. Temporarily disable communication with the server.
3. Click on tabs in the following sequence: 1 - 2 - 3 - 2 - 1.
4. Enable communication with the server.
5. You should note that the contents of the first tab are displayed, but not the tab itself. That is, no tab is selected.

The test program can be invoked with a URL parameter of "?polished" to test with the "polished" theme. Unlike with the "bootstrap" theme, the first tab should appear selected after this sequence.

The request/response pairs along with headers are provided in a second attached file: queue_style_issue_log_20130419c.txt

This issue can also currently be observed on the Wt site's tab widget example at: http://www.webtoolkit.eu/widgets/navigation/tab-widget

In this case, just click the first three tabs in sequence: "First" - "Preload" - "Style" - "Preload" - "First", before re-enabling communication.

A potential fix for this issue will be posted shortly on github and I will update this report with a link.