When I tear off a panel, is there a way to have a panel displays in front the rest of the panels?
Not without making a new window, showing the same editor and the same panel in it, and having a window manager that can keep that window in front of other windows.
As far as I know, this is a longstanding feature in Blender. When Ton first designed the interface, some other 3D programs at the time had interfaces with numerous pop-up windows coming and going all the time. Ton didn’t like this, and wanted something more clean. So Blender mostly uses an expanding / collapsing interface instead, and won’t give you a pop-up window unless you tell it to.