Drawing error when border size set to zero.

[lendres]

Describe the bug
There appears to be a minor issue with the borders if the border size is set to zero.

To Reproduce
Steps to reproduce the behavior:

1. Using the sample, go to 'Settings'
2. Set the 'Border Thickness' to zero (Click on the '-" button until it darkens).
3. Close the settings and observe the vertical border between different columns. Resizing the window may be necessary to see the issue.
4. Resizing the window causes the vertical border issue to appear, disappear, or move. There may be zero, one, or more than one vertical border.

Expected behavior
When the border size is set to zero, no vertical borders should be visible.

Screenshots
First example:

After changing the size of the window, the bar has moved:

Desktop (please complete the following information):

• OS: Windows
• Version 10.0.19044
• Maui.DataGrid version 4.0.3

[symbiogenesis]

I had seen this before, at some point.

I think this is a windows-only bug in upstream MAUI or WinUI

We use a combination of background color and padding at the DataGridCell level to efficiently produce a border effect. Compared to the slow Border controls. I had tried using ColumnSpacing at the DataGridRow level but I think it had some problems.

Using an actual Border control wouldn't help, either, since apparently resizing Border controls on Windows is likewise problematic. dotnet/maui#20407

The current approach of doing borders at the cell-level in general probably isn't ideal, because the widths are actually doubled. So if you want borders that have a width of 1, you would need to set BorderThickness to 0.5

Perhaps refactoring to using ColumnSpacing will work better today than in the past.

[symbiogenesis]

I can reproduce it but only if I resize to very specific widths. The initial width doesn't show it.

[symbiogenesis]

Just tried it. Using ColumnSpacing works but has the same issue.

#180

[symbiogenesis]

There was a bugfix in MAUI recently that may be related.

dotnet/maui#21197