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Top-level forms scale minimum and maximum size to DPI

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Top-level forms in Windows Forms now scale their MinimumSize and MaximumSize values according to the dots per inch (DPI) of the monitor when running in HighDpiMode.PerMonitorV2 mode.

Version introduced

.NET 8 Preview 1

Previous behavior

In .NET 8, the MinimumSize and MaximumSize values for top-level forms remained constant regardless of the application DPI mode and the DPI of the monitor where the form is rendered. This sometimes resulted in scaling limitations of the top-level form.

You can also opt into this behavior in .NET 7. To opt in, set the System.Windows.Forms.ScaleTopLevelFormMinMaxSizeForDpi runtime configuration option described in the Recommended action section.

New behavior

Starting in .NET 8, top-level forms scale their MinimumSize and MaximumSize values according to the DPI of the monitor when running in HighDpiMode.PerMonitorV2 mode. The behavior of your app might change in the following ways:

  • Run-time dependencies might be impacted when the minimum and maximum size of the form change.
  • New MinimumSizeChanged and MaximumSizeChanged events might be raised.
  • The scaled form size now has new constraint values for the minimum and maximum sizes.

Change category

This change is a behavioral change.

Reason for change

This change is part of a broader effort to improve the Windows Forms user experience on high DPI monitors. It enables developers to set minimum and maximum sizes for top-Level forms without having to take the DPI of the monitor into account.

If the new behavior is problematic for you, you can opt out by setting System.Windows.Forms.ScaleTopLevelFormMinMaxSizeForDpi to false in your runtimeconfig.json file.

runtimeconfig.template.json template file:

{
   "configProperties": {
      "System.Windows.Forms.ScaleTopLevelFormMinMaxSizeForDpi": false
   }
}

[appname].runtimeconfig.json output file:

{
   "runtimeOptions": {
      "configProperties": {
         "System.Windows.Forms.ScaleTopLevelFormMinMaxSizeForDpi": false
      }
   }
}

Affected APIs

N/A

See also