Python 2.7.15 Idle-GUI, a drawing glitch in the "Open module"-expansion-triangle when hovering the neighbor item "Recent files", the expansion triangle is off-by-one

Reproduction steps

• VBox4.3.12 + VBEMP
• install Python 2.7.15 from rapps (it's a GTK app iirc, it's about tab states "Tk 8.5.15")
• run its GUI, called "Idle"
• open the menubar "file" and hover with the mouse over the entries

Observed result
Whenever you hover with the mouse over item "Recent files", the neighbor item "Open module" gets corrupted by a drawing glitch at its expansion triangle
The expansion triangle is off-by-one, it should be visible for "recent files", but not at "Open module"
0.4.13-RC-41-gc6b2f3a_affected.webm
0.4.13-RC-41-gc6b2f3a_affected.log is useless, as ros logs nothing when hovering

Expected result
no drawing glitch
Expansion triangle should be after "Recent Files" actually, it's offbyone in ros
2k3sp2.webm