#define WINDOW_RIGHT_MARGIN(W) \
(WINDOW_RIGHT_EDGE (W) \
- (! FRAME_HAS_VERTICAL_SCROLL_BARS (XFRAME (WINDOW_FRAME (W))) \
- ? 1 \
+ ? ((WINDOW_RIGHTMOST_P (W)) ? 0 : 1) \
: FRAME_HAS_VERTICAL_SCROLL_BARS_ON_RIGHT (XFRAME (WINDOW_FRAME (W))) \
? FRAME_SCROLL_BAR_COLS (XFRAME (WINDOW_FRAME (W))) \
: 0))