Summary

Fix hscroll() function on Windows by using MOUSEEVENTF_HWHEEL instead of MOUSEEVENTF_WHEEL.

The previous implementation of _hscroll() in _pyautogui_win.py simply called _scroll(), which uses MOUSEEVENTF_WHEEL (vertical scroll event). This caused horizontal scrolling to behave exactly like vertical scrolling.

Now _hscroll() properly uses MOUSEEVENTF_HWHEEL (0x01000) to send horizontal scroll events as documented in the Windows API.

Changes

• Modified _hscroll() function in pyautogui/_pyautogui_win.py to use MOUSEEVENTF_HWHEEL flag
• Added proper coordinate boundary checking (consistent with _scroll() implementation)

Related Issues

• Partially addresses scroll mouse not working in windows #440 (scroll mouse not working in windows)
• Related to Using Direct Input on windows #442 (horizontal scrolling mentioned)

Related PRs

• Alternative to hscroll in _pyautogui_win.py #656 (hscroll in _pyautogui_win.py) - simpler implementation without changing function signatures
• Related to Fix Windows mouse wheel #895 (Fix Windows mouse wheel)
• Related to Fix scroll() #920 (Fix scroll())

Test Plan

• Test pyautogui.hscroll(3) scrolls right on Windows
• Test pyautogui.hscroll(-3) scrolls left on Windows
• Verify pyautogui.scroll() and pyautogui.vscroll() still work correctly