[Regression][Mixed DPI] Classic Win32 checkbox renders incorrectly after Windows 11 24H2/25H2 update (build 26200.8875+)

전대일 40 Reputation points
2026-07-27T03:38:58.71+00:00

After a recent Windows 11 update, standard checkboxes in classic Win32 applications (Visual Styles / Common Controls v6 NOT enabled, and DPI-unaware) render incorrectly on mixed-DPI multi-monitor setups. This is a regression: it does not occur on earlier builds and disappears when the update is uninstalled.

Symptom: the checkbox box is offset; the check glyph is the wrong size/position; the caption alignment is also incorrect. Always reproducible in the same environment.

When (build comparison): 26200.8655 = OK (not reproduced); 26200.8875 = reproduced; 26200.8894 (latest) = still reproduced. The regression was introduced between 26200.8655 and 26200.8875. Candidate updates: KB5095093 (26200.8737) or KB5101650 (26200.8875, 2026-07-14).

Environment: Windows 11 25H2 (build 26200.x) confirmed; 24H2 (26100.x) likely affected (same servicing base). Mixed-DPI multi-monitor, e.g. primary 1920x1080 @100% + secondary 3840x2160 @300%.

Triggering condition: occurs only when the app window is shown on a monitor whose scale is HIGHER than the primary monitor. It renders correctly on the primary monitor.

Steps to reproduce: (1) Windows 11 build 26200.8875 or later. (2) Two monitors at different scale factors (e.g., 100% and 300%). (3) Run a classic Win32 app that is DPI-unaware (no dpiAware manifest) and does NOT enable Visual Styles (no Microsoft.Windows.Common-Controls v6), containing standard checkboxes (e.g., built with a legacy toolchain such as Delphi 2007). (4) Move the window to the higher-scale (non-primary) monitor. Result: the checkbox box and check glyph are rendered at the wrong size/position. A minimal reproduction sample can be provided.

What we confirmed - renders correctly when: all monitors use the same scale (100%); the update is uninstalled; the higher-scale monitor is set as the primary (reboot); or Visual Styles (Common Controls v6) are enabled. No effect: Compatibility "Override high DPI scaling behavior" (Application / System / System (Enhanced)).

Analysis (hypothesis): without Visual Styles, classic checkboxes appear to be drawn via DrawFrameControl, which does not participate in DPI virtualization and seems to size the glyph using the primary monitor's DPI. Under mixed DPI this misaligns the glyph and the box on a higher-scale monitor. A recent update appears to have changed this behavior.

Request: since uninstalling the update restores normal behavior, this appears to be a Windows regression. Could you confirm this issue and advise on a fix, a Known Issue Rollback (KIR), or official guidance? Legacy Win32 applications that use classic common controls without Visual Styles are affected. We can provide a minimal reproduction sample, screenshots, and logs on request.

Win11_Checkbox_Regression_Report.txt

Win11_CheckBox_Rendering_ExpectedWin11_CheckBox_Rendering_Expected

**Win11_CheckBox_Rendering_Bug
**Win11_CheckBox_Rendering_Bug

Windows for home | Windows 11 | Display and graphics
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  1. Lucus-V 13,485 Reputation points Microsoft External Staff Moderator
    2026-07-27T16:50:02.7466667+00:00

    Hi 전대일,

    Thank you for the detailed report and for the extensive troubleshooting you have already performed.

    Based on the information provided, we understand that standard checkbox controls in a classic Win32 application are rendering incorrectly after installing recent Windows 11 updates. The issue appears to affect DPI-unaware applications that do not use Visual Styles (Common Controls v6) when running in mixed-DPI multi-monitor environments, specifically when the application window is displayed on a monitor configured with a higher scaling factor than the primary display.

    We appreciate the comparison testing you performed across multiple Windows builds and the confirmation that the behavior does not occur on earlier builds. The fact that uninstalling the update restores the expected rendering behavior suggests that this may be a regression introduced by a recent Windows servicing update.

    At this stage, we are not aware of any publicly documented Known Issue Rollback (KIR) or official fix that specifically addresses this scenario.

    I really wish I could assist you directly on this issue. However, the behavior you're experiencing is tied to back‑end systems and service functionality, and unfortunately, we don't have the authority or access required to investigate or make changes at that level.

    Please note that this is a user-to-user support forum. Moderators, contributors including external Microsoft employees cannot directly intervene in Microsoft product features or access back-end systems. Our role is limited to providing technical guidance on reported issues, requests, or ideas.

    Given these limitations, the most appropriate avenue for product changes or feature requests is to Send feedback to Microsoft with the Feedback Hub app.

    Thank you for your understanding, and I hope the support team can resolve this for you soon.

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  2. Onur Asker 0 Reputation points
    2026-08-06T14:28:00.74+00:00

    We are experiencing exactly the same issue after installing Windows 11 Build 26200.8875 (KB5101650).

    Our applications are developed with Delphi 7 and worked correctly before this Windows update. After the update, the CheckBox, RadioButton, and CheckListBox check indicators became noticeably larger than before. The rest of the user interface appears normal.

    We tested the following without success:

    Removing the DPIUNAWARE compatibility setting

    Changing Windows DPI scaling settings

    Testing with and without application compatibility options

    The problem affects multiple Delphi 7 Win32 applications, which strongly suggests this is a Windows regression rather than an application issue.

    Can Microsoft please confirm whether this is a known issue and whether a fix is planned for a future Windows update?

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  3. NickH 0 Reputation points
    2026-09-27T17:55:05.4866667+00:00

    I can confirm similar behavior that only appeared recently. Currently on 26200.9457. The legacy application is Carlson Hulls Designer.

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