Created attachment 121062 [details]
screenshot showing the problem

SUMMARY

In previous releases, when the panel width is less than the width of the screen, the application launcher menu would align itself so that moving vertically after clicking the launcher in the panel would end up in the left-most entry, Favorites. However, since 5.16, the behavior has changed and the launcher menu is centered with the launcher in the panel. This makes it difficult to reach the Favorites as moving the mouse vertically down switches the page to Applications (by default, these can be reordered).

STEPS TO REPRODUCE
1. Reduce panel width to not span the entire desktop
2. Click on the application launcher
3. Move to nearest point in the menu.

OBSERVED RESULT

The nearest point in the menu causes the menu to change page to the item closest to the center, not the item on the left most end, which is in fact what is shown by default (implying a default selection).

EXPECTED RESULT

The menu should be aligned with the panel so that the left most page gets selected if the mouse moves from the launcher button to the launcher menu. This may need to be different for RTL languages, I imagine. Generally, aligning the menu popup to the extent of the panel should work for both cases.

ADDITIONAL INFORMATION

See attached screenshot.