The cursor isn't visible on HDR displays

[zadjii-msft]

My primary monitor in the basement is a 3440x1440, 100% display. I'm on dark mode. The cursor in the search box isn't visible there.

[zadjii-msft]

@crutkas this is what you're seeing with the cursor on light theme too

[zadjii-msft]

Oh no the snipping tool can't capture this!

I tried messing with the styling here, to see if one of these brushes was getting evaluated weird. Alas, if I opened the snipping tool, the caret changes to the correct one!

Setting the background to something insane did highlight though that in this state, the cursor is dark grey, like the BG of the control. Just gotta figure out which brush is the weird one.

[zadjii-msft]

Yep okay I think I figured out where the problem is. Not how to solve it, but what the problem is.

Setting the <Setter Property="Background" in TextBox.xaml is what hides this. I think WinUI itself calculates the caret background based on the Background that the cursor is actually going to get displayed on. And it's smart enough to account for everything in the template itself, but nothing outside of the template.

AND MOST IMPORTANTLY - it doesn't know how to do this logic on 100% scaled displays, for whatever reason.

microsoft/microsoft-ui-xaml#8207 is the thread that they dupe issues too, but that's bY dEsIgN

IMO our only option is to adjust the text box styling so that it covers the entire "titlebar" area, with padding for the search/back icon, and give that a semi-transparent background (enough to trick WinUI into giving us a cursor). Since a WinUI fix is probably impossible.

[zadjii-msft]

Yea, this isn't trivially solvable either. The Rectangle that renders the caret is CompositeMode=DestInvert, and it sets that manually:

https://github.com/microsoft/microsoft-ui-xaml/blob/ffe33f9b7d0e9f5a2ca3330d0ce329f09dff092b/src/dxaml/xcp/core/native/text/Controls/TextBoxView.cpp#L2797-L2798

but why doesn't ElementCompositeMode::DestInvert on a 1dip wide rectangle invert the background on 100% scale, when it does on a 125%?

[zadjii-msft]

[zadjii-msft]

MSFT:14726922 looks like the upstream

[crutkas]

For me I can see it on dark but not light