[Gabriel Dufresne (GabrielDuf)]

This pull request adds logic to improve window resizing behavior by implementing custom hit testing for the window borders. The main changes include defining additional hit test constants, adding a new HitTestResizeBorder method, integrating this logic into the window procedure, and adding a native interop method for retrieving the window rectangle.

Window resizing and hit testing improvements:

• Defined additional hit test constants (HTLEFT, HTRIGHT, HTTOP, HTTOPLEFT, HTTOPRIGHT, HTBOTTOM, HTBOTTOMLEFT, HTBOTTOMRIGHT, HTNOWHERE) to support more precise window edge detection.
• Added the HitTestResizeBorder method to determine which border or corner of the window is being interacted with, enabling custom resize behavior.
• Integrated the new hit test logic into the window procedure (OnWindowsWndProc) to handle WM_NCHITTEST messages and return the appropriate hit test result, allowing for correct window resizing from all edges and corners.

Native interop enhancements:

• Added a P/Invoke declaration for GetWindowRect in the NativeMethods class to retrieve the window's dimensions, which is used in the hit testing logic.

[Copilot]

Copilot review overview

🟡 Changes recommended

Caption-button hit testing takes precedence and prevents resizing along overlapping top-right borders.

Review effort: Balanced
Findings: 1

Open (1)

• Resize hit testing is bypassed near caption buttons · New

What changed in this PR

Adds custom Win32 resize-border hit testing for the Avalonia main window.

Changes:

• Detects all resize edges and corners.
• Handles WM_NCHITTEST using calculated border regions.
• Adds GetWindowRect interop.

File	Description
src/​UniGetUI.Avalonia/​Views/​MainWindow.axaml.cs	Implements native resize-border hit testing and required interop.

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[Copilot]

Copilot review overview

🔵 Needs a closer look

Native window hit testing requires manual validation across DPI levels, monitor layouts, snapping, and window states.

Review effort: Balanced
Findings: None

Resolved since last review (1)

• Resize hit testing is bypassed near caption buttons

[randy-but-a-ro]

🤖 Pull request was approved automatically: the AI review is complete and all its review threads are resolved. 🎉

Integration Details

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