The simple, yet powerful, status bar for Xorg.

#FORK

This patch enhances sxbar so that workspace boxes on each monitor and only show windows actually present on that monitor — like dwmbar.

• Added visual workspace window boxes (max 4)

• Per-monitor window counting:
  Workspace boxes now only count windows located on the current monitor, instead of showing all windows across all screens.

• New helper function:
  Added window_on_monitor(Window win, int monitor_index) to determine if a window belongs to a specific monitor.

• Workspace box logic update:
  The workspace box drawing code now uses this function to filter windows per monitor.

• Each sxbar instance displays accurate workspace status for its own screen.
• Workspace boxes are informative and reflect the window layout on each monitor.