Based on my discussion with Chris, on MacOSX:

• work on the nightly build
• does NOT work on the stable 4.2.2-1

It is not OS dependent. I observe the same thing on Linux.

Issue has been identified.

The recent changes allowing to fetch on demand extensions when scrolling required to extend the QWebkit object embedded in Slicer so that it emulates part of the HTML5 Visibility API.

This was done while working on Slicer issue 2911, and the associated changesets are Slicer r21660 [2] and SlicerAppStore commit fd86adc7 [3]

When the slicerappstore page is loaded, it checks if the browser has support for
PageVisibility API [4]:

// Setup scroll pagination and fetch results based on the initial settings
if ($.support.pageVisibility){

[...]

} else {
// If visibility API is not supported, fetch all extensions

[...] // Here is the logic to fetch if no pageVisibility API support

}

The problem occurred when clicking on a category. Indeed, the javascript callback associated with the click event was "applyFilter()" and this function wasn't checking if the pagevisiblity API was present and was assuming the "fetch on demand" mode was enabled. Then a "loading gif" was displayed bu no extension were fetched .. it then give the impression of "hang".

[1] http://na-mic.org/Mantis/view.php?id=2911
[2] http://viewvc.slicer.org/viewvc.cgi/Slicer4?view=revision&revision=21660
[3] https://github.com/midasplatform/slicerappstore/commit/fd86adc72671858340f881528408b0db181cf2d4

[4] https://github.com/midasplatform/slicerappstore/blob/fd86adc72671858340f881528408b0db181cf2d4/public/js/index/index.index.js#L317

This has been fixed in the slicerappstore midas plugin. See https://github.com/jcfr/slicerappstore/commit/fb3e94343df37c69f32f9ffc766211c79b88aa6d and https://github.com/midasplatform/slicerappstore/pull/37

As soon as the change have been reviewed, integrated and the server update. It should be possible to click on the category using from Slicer 4.2.2-1.

Changes have been reviewed, integrated and tested.

@chris: Issue can be closed

Thanks