[Gabriel Dufresne (GabrielDuf)]

• I have read the contributing guidelines, and I agree with the Code of Conduct.
• Have you checked that there aren't other open pull requests for the same changes?
• Have you tested that the committed code can be executed without errors?
• Have you confirmed that this issue is caused by UniGetUI itself, and not by the package manager or the package involved?

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Root cause

The custom Windows caption strip is right-aligned in a client area that covers the whole window: the WM_NCCALCSIZE hook returns 0, so the WS_THICKFRAME band (about 8 px at 100%, more at higher DPI) is visible client area. #5477 added MainWindow.UpdateCaptionButtonInset, which measured that band and pushed the strip left by it. #5590 kept the measurement but set CaptionCloseButton.Width = 46 + inset and Padding = (0,0,inset,0). The Close button's background is the full Button bounds, so on a restored window its gray and red hover fill became wider than Minimize and Maximize, and the right padding centred the X over the left 46 px only, leaving it off-centre in the visible button. Maximized, the inset is 0, which is why it only shows on a restored window.

The extra width was never needed for hit-testing: #5477 also made WM_NCHITTEST return the side and corner resize edges (HitTestResizeBorder) before testing the caption buttons, and that ordering keeps the outer band resizing.

Fix

Removed the per-state inset adjustment. Close is now the same fixed 46x44 button as Minimize and Maximize, flush with the window's right edge, with the X centred by the caption style's Padding=0. Deleted UpdateCaptionButtonInset, its two callers (the WM_SHOWWINDOW/WM_SIZE post goes back to Dispatcher.UIThread.Post(cornerOwner.UpdateWindowCornerPreference)), and the unused x:Name="CaptionCloseButton". The hit-test ordering from #5477 is kept. Close reaches the window edge (#5571) and the three buttons are identical with a centred glyph (#5637).

Verification

• dotnet build src/UniGetUI.Avalonia/UniGetUI.Avalonia.csproj -p:Platform=x64 -p:UseSharedCompilation=false exited 0 with 0 errors (warnings are unrelated analyzer and obsolete-API ones; not compared against a baseline).
• dotnet format whitespace and dotnet format style --verify-no-changes on the changed files exited 0.
• Not checked visually: no screenshots were taken. Please check the restored-window caption row at 100% and a higher DPI.
• The full test suite is left to CI.

Regression test

None added. The bug is native window-chrome layout driven by a live Win32 HWND (IsZoomed, GetDpiForWindow, AdjustWindowRectExForDpi inside the WM_SHOWWINDOW/WM_SIZE hook). No unit test can reach that without a real top-level window, and after the fix no logic is left: the button is a static 46x44 declaration.

Review notes (non-blocking)

• Known trade-off carried over from Extend the Close button to the window's right edge #5590: on a restored window the rightmost frame-width pixels (about 8 px at 100%) of the Close button return HTRIGHT from HitTestResizeBorder, which runs before the caption-button hit test, so they resize instead of closing while the hover fill can still show there. Changing the order would bring back the Skip installers already on disk and make bundle downloads resolve a real version #5469/Let the resize border win over the caption buttons on the side edges #5477 behaviour.
• Maximized state is unchanged. The immersive dialog close button (second caption caption-close in MainWindow.axaml) was never touched by Extend the Close button to the window's right edge #5590 and is left alone.
• Pre-existing, not caused by this diff: dotnet format style src/UniGetUI.Windows.slnx --no-restore --verify-no-changes exits 2 because of IDE0060 at src/UniGetUI.PackageEngine.Tests/CargoManagedOperationRoutingTests.cs:155 (unused cancellationToken). The same command scoped to UniGetUI.Avalonia.csproj exits 0.

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Closes #5637

🤖 Generated with Claude Code

[Copilot]

🔵 Needs a closer look

The caption-button fix lacks live Windows verification of alignment, glyph centering, and edge-resize behavior in restored and maximized states at 100% and higher DPI.

No open issues 🎉

What changed in this PR

Fixes the restored-window Close button’s unequal width and off-center glyph by removing its dynamic inset adjustment. This addresses #5637 while preserving right-edge alignment and resize hit-testing.

Changes:

• Keeps Close at the same fixed 46×44 size as the other caption buttons.
• Removes the inset calculation and its startup/window-state callbacks.
• Removes the unused Close button name from XAML.

File	Description
src/​UniGetUI.Avalonia/​Views/​MainWindow.axaml.cs	Removes dynamic Close button sizing and simplifies the window-state callback.
src/​UniGetUI.Avalonia/​Views/​MainWindow.axaml	Removes the unused button name while retaining fixed dimensions and caption styling.

_{Review effort: Balanced}

[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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