I see this weird progress bar in AppStore on Yosemite, which keeps disappearing all the time. When you switch tabs, it is there for some seconds, then gone again.
Out of interest, I tried to figure out, what kind of bar it is and why that is happening, but can't find anything similar on google images.
In IB there is only the NSProgressIndicator, looks different and cannot configure it to look like the AppStore bars, so I guess they are using sth else?
The disappearing effect is happening on all Yosemite devices I know .. saw it happen both in the Mac AppStore and in the XCode->Preferences->Downloads screens.
Not sure anymore about iOS, but thought I saw it there too.
Any idea what element it is and what the folks at apple might be doing wrong?
I moused over it with the Accessibility Inspector, and it appears to be a Web view. So that progress bar is probably styled in HTML and CSS, and is not a native control.