Redmine

I think it is better to show the indicator at the center of the page than at the top of the page.

Suppose that the user right-clicks the issues list. Since the indicator is now positioned at the center of the page, it stands out well. If the patch applied, the user may overlook the indicator because it is small and displayed at the position far from the point the user looks. I think the user looks near the mouse cursor, not at the top of the page when the indicator is shown.

Go MAEDA wrote:

I think it is better to show the indicator at the center of the page than at the top of the page.
Suppose that the user right-clicks the issues list. Since the indicator is now positioned at the center of the page, it stands out well. If the patch applied, the user may overlook the indicator because it is small and displayed at the position far from the point the user looks. I think the user looks near the mouse cursor, not at the top of the page when the indicator is shown.

Your re absolutely right, and it's how it mostly used to be done back then I believe, but IMHO IMHXP (in my humble experience ;D) it seems right only for the first X amount of possible right clicks on the issue list, to get the context menu displayed, after which the never ending blinkness of a loading bar may successfully get quite annoying :D

By moving it up-top, just like nearly everywhere these days (either up-top or upper left corner if it's a spinner, e.g. Google, YouTube and etc, of-course they use something like NProgress.js which is more slim, but still...), at least it's kind of offloading it from the central vision, in the favor of peripheral vision a little bit more, which means loading indication gets to be more of something that's optional rather than forced into the eyes each time.
I thought about it a little like driving a car and occasionally looking at a cockpit to check speed and other readings and Redmine is anyway the software that would require little bit of familiarization with interface on user's end, not mentioning variety of themes you can possibly install.

An alternative however could be to bin with that bar altogether (as proposed here #30167), at least on context menu displays and utilize system waiting cursors instead, because honestly, why not, it's already built-in and free :D Then for everything else but context menu, this loading bar could be kept at the center if it's so desired then.

P.S. I also noticed that currently, ajax loading bar has unconstrained % based width, it can get extremely wide on ultra-wide displays :D