when dragging app tabs onto dock icons expand those to show multiple windows

[ronso0]

Right now, the workflow for dragging web browser tabs from one browser window to another is rather cumbersome IMO, I have to tile windows side by side on my desktop to do so.

Current situation:
* I have multiple browser windows open
* I want to move a tab from window1 to window2
* the dock expands when dragging a tab onto it but I can't select the
  target window.
Unfortunately I can't use Alt+Tab to switch windows while dragging a tab, maybe that's specific to apps and desktop environments?
I run Firefox in Ubuntu 20.04 with Xfce 4.14

Solution A
* pick a tab, drag it onto the icon which indicates multiple windows
* app icon expands
 = show icons for each window side by side
* drag tab onto a menu item (window), show window title
 = window is activated, preferrably after the OS-specific
   drag'n'drop delay
 = tab can be dropped at desired position in tab bar

Solution B
* pick a tab, drag it onto the icon which indicates multiple windows
 = the regular context menu opens
* drag tab onto desired target window icon
 = window is activated, preferrably after the OS-specific
   drag'n'drop delay
 = tab can be dropped at desired position in tab bar

Somehow related:
lp:1622161 Add option to display # of icons for the same amount of # of windows of the same application

[ronso0 (ronso0)]

I guess the context menu Solution A is easier to implement right now as it already provides the window title. (currently hovering an dock icon only shows the App name, not the window title)