fix: TitleBar respects ResizeMode.NoResize#1719
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Add ResizeMode check in GetWindowBorderHitTestResult. Return HTNOWHERE when ResizeMode is not CanResize or CanResizeWithGrip. Fixes regression introduced by PR lepoco#1560 where NoResize windows remained resizable.
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May 15, 2026
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Pull request overview
Fixes a regression in TitleBar non-client hit-testing so windows with ResizeMode="NoResize" (or CanMinimize) cannot be resized via border dragging when ExtendsContentIntoTitleBar=True.
Changes:
- Adds a
ResizeModegate toGetWindowBorderHitTestResultto returnHTNOWHEREwhen the window is not resizable.
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| var window = Window.GetWindow(this); | ||
| if (window?.ResizeMode != ResizeMode.CanResize && window?.ResizeMode != ResizeMode.CanResizeWithGrip) | ||
| { | ||
| return IntPtr.Zero; | ||
| } |
Return PInvoke.HTNOWHERE explicitly instead of IntPtr.Zero when resize is disabled Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
Use existing _currentWindow cache for ResizeMode check
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Add ResizeMode check in GetWindowBorderHitTestResult. Return HTNOWHERE when ResizeMode is not CanResize or CanResizeWithGrip. Fixes regression introduced by PR #1560 where NoResize windows remained resizable.
Pull request type
Please check the type of change your PR introduces:
What is the current behavior?
When a FluentWindow has
ResizeMode="NoResize"(orCanMinimize) and contains a TitleBar withExtendsContentIntoTitleBar="True", the window can still be resized by dragging its borders.This is because
GetWindowBorderHitTestResult()returns resize hit-test values (HTLEFT/HTRIGHT/HTTOP/HTBOTTOMetc.) without checking the window'sResizeModeproperty.Issue Number: N/A
What is the new behavior?
ResizeModecheck at the beginning ofGetWindowBorderHitTestResult()IntPtr.Zero(HTNOWHERE) whenResizeModeis notCanResizeorCanResizeWithGripResizeMode="NoResize"orResizeMode="CanMinimize"can no longer be resized via border draggingCanResizeandCanResizeWithGripOther information
Affected versions: v4.1.0 - v4.3.0 (regression introduced by PR #1560)
Tested on: v4.3.0
Minimal repro XAML: