[broken DEEPER than NOTEPAD!] Scrolling-down-while-being-in-text-selection-mode does not work

Reproduction steps

• Open a document in Notepad that has enough text that it allows scrolling, e.g. our readme.txt
• Start selecting text in the middle of the current view, and move the mouse-cursor downwards while keeping the mouse button pressed all the time
• Move the mouse cursor so far to the bottom that you are outside of the notepad view

Expected result
If you perform this procedure with ros notepad executed under Windows, it will properly scroll the text downwards, while continuously extending the text selection

Observed result
If you perform this procedure with ros notepad executed under ros it will not really scroll downwards.
0.4.15-dev-7842-g558ab78_ScrollingDownWhileBeingInTextSelection_doesNotWorkProperly.webm
0.4.15-dev-7842-g558ab78_ScrollingDownWhileBeingInTextSelection_doesNotWorkProperly.log (is useless, nothing is logged while it misbehaves like that)

Since our notepad is working fine under Windows, we can deduce that this is maybe broken in Win32SS? or comctl32?. Definitely no bug in notepad.