The current size set to these buttons is too small when in HiDPI. And toolbar doesn't resize buttons for HiDPI, so we will need to reset it with TB_SETBUTTONSIZE manually.
On Windows with a 250% scale: ![before](/uploads/940809f0147ccc11299e216e102cf19d/before.PNG)
vs
![after](/uploads/878699945699579f683d005b53ef7a1f/after.PNG)