MicrosoftForm Size Is Not Updated Correctly When DPI Scaling Exceeds 200

[vimalrajsf5014]

Description

When adding a control of size 500x500 pixels (at 100% scaling = 96 DPI) to a Microsoft Form, the control is anchored and its size is measured at different points in the lifecycle:

• After InitializeComponent
• After OnHandleCreated
• At 100% scaling, these measurements are identical.
• At DPI scaling greater than 200%, the control size differs depending on when it is measured, which causes layout problems.

I have attached a simple sample project and images that demonstrate the issue.

Screenshots

• 100% Scaling:

• 125% Scaling:

• 150% Scaling:

• 175% Scaling:

• 200% Scaling:

• 225% Scaling:

• 250% Scaling:

• 300% Scaling:

• 350% Scaling:

• 400% Scaling

• 450% Scaling

• 500% Scaling

SimpleSample

MicrosoftFormSimpleSample.zip

Steps to Reproduce

Step 1 : Run the attached simple sample project.
Step 2 : Click the MicrosoftForm button.
Step 3 : Ensure that DPI awareness is set to true in the app.manifest file.
Step 4 : The sample creates a control sized 500x500 pixels at 100% scaling (96 DPI) and anchors it to the parent form.
Step 5 : Observe the control size measured:

• After InitializeComponent
• After OnHandleCreated

Step 6 : Change the display scaling level to 200% or higher (e.g., 225%).
Step 7 : Compare the measurements — they should be the same, but at scaling >200% the values differ.

Actual Behavior

• For DPI scaling greater than 200%, the control’s size measured after InitializeComponent and after OnHandleCreated differs.
• This mismatch causes layout problems and breaks anchored layouts.

Expected Behavior

• The control size should remain the same between creation and display, regardless of the DPI scaling level.
• Anchored layouts should not break due to differences between InitializeComponent and OnHandleCreated measurements.

Questions

• Is this a known WinForms rendering issue when controls are anchored on high DPI displays (scaling >200%)?
• Does the size mismatch impact layout consistency, usability, or accessibility in applications?
• Are there any recommended workarounds or fixes (e.g., measuring after OnHandleCreated, adjusting DPI awareness, or other approaches)?

Environment

.NET Framework / .NET: .NET Framework
Windows Version: Windows 11
Display Scaling Tested: 125%, 150%,175%,200%, 225%,250%,300%,350%,400%,450%
Control Behavior: Control is anchored to the parent form
Custom Styling: None applied

Additional Notes:

• No custom drawing or styling is used.
• Issue persists consistently across multiple scaling levels when the control is anchored.
• The confusion arises because the size differs depending on whether it is measured after InitializeComponent or after OnHandleCreated

[vimalrajsf5014]

Hi Team, any updates on this issue?

[LeafShi1]

Based on the steps you provided, we were unable to reproduce your problem. Please point out any discrepancies between my actions and yours.

Recording.2026-01-12.150753.mp4

[vimalrajsf5014]

Thank you for testing across different DPI settings. The display resolution of 1920x1080 reliably reproduces the reported issue. I have attached the system details and a video for your reference.

System Details

Edition : Windows 11 Enterprise
Version : 24H2
Installed on ‎: 1/‎13/‎2025
OS build : 26100.7462
Experience : Windows Feature Experience Pack 1000.26100.275.0
Display Scaling Tested: 125%, 150%, 175%, 200%, 225%, 250%, 300%, 350%, 400%, 450%
Control Behavior: Control is anchored to the parent form
Custom Styling: None applied
Display Resolution: 1920x1080

ReplicateVideo
ReplicateVideo.zip