[HDPI] CheckListBox with multi-items is not scaled well

[Olina-Zhang]

• .NET Core Version: 3.0.100-preview8-013334
• Have you experienced this same bug with .NET Framework?: Yes

Repro Steps:

1. Set Windows DPI as 100%, then create a Winforms .Net Core application
2. Add CheckListBox control to form designer, and add 4 lines items to this control, ensure all items are shown without scrollbar and no extra empty line --- use .Net framework app designer code to workaround since .net core designer is not fully supported so far
3. In program.cs file, add one code line to support HDPI: SystemAware mode:
   Application.SetHighDpiMode(HighDpiMode.SystemAware);
4. Build and run this application
5. Set Windows DPI as 300%, and run this application again

Actual behavior:
On 300%DPI, CheckListBox is not scaled well, there has one extra empty line shown. This issue also repro in 150%, 250%DPI.

Expected behavior:
On 300%DPI, it should have 4 lines items shown on form designer in runtime, as same as 100%DPI
Here is the 100% screenshot

[vladimir-krestov]

Hi @Vino-Wang, could you please check this point? I guess CheckListBox works well now.

Result:

Environment:

• .NET Core SDK [5.0.100-alpha1-015748]
• Microsoft Windows [Version 10.0.18363.476]

[RussKie]

⚠️ We are currently blocked from flowing through to .NET5 setup (dotnet/wpf#2118), so there only way to test this would be via private binaries.

[dreddy-work]

@Olina-Zhang , if this doesn't repro in latest , please close it.

[kirsan31]

Can't repro this with .net 5.0.3. on Win10 20H2.

[Olina-Zhang]

@Olina-Zhang , if this doesn't repro in latest , please close it.

It also cannot repro in the latest 6.0 SDK build.