Can you please provide steps to reproduce the problem?
Here we just dropped a TScrMemo, TScrPascalMemoStyler, associated both, selected "Windows 10 Dark" theme in project options, Application, Appearance, and all works fine.
Well, you said "Now, the +=-{} are so dark as to not be readable."
You can use TScrPascalMemoStyler.CommentStyle variable and change to the color you want. The component has all the settings for you to set the colors you want.
Right, I said that and it is true for me, not readable <> not visible.
Our users can select the theme they want to use. If I set the color to white, for example, and the user selects a different theme, a lighter theme, then back to square one.
TScrPascalMemoStyler doesn't have a different color set for each possible theme your application might have. It will be up to you to know which is the selected them and set the proper colors in TscrPascalMemoStyler properties to match the look and feel you want for that specified theme.
OK, if the TScrPascalMemoStyler does not contain the colors, where do colors come from? What changes the colors in the memo for the comments from X to Y and numbers from A to B because of a theme change? I am new to themes.
I mentioned an example in a post above: You can use TScrPascalMemoStyler.CommentStyle property to change the color of comment.
You said you didn't like dark blue for comments, so just go to that property and change the color from dark blue to something else you like. That's the same for all other colors, you have properties like AllStyles, HighlightStyle, NumberStyle, all those properties can be used to set colors displayed by TScrMemo.
OK, so the themes change the color of the TScrMemo background color and not of the text colors. On other controls I see the StyleElements property and I can set the seClient to false to prevent the theme logic from altering the client area.
That property is not exposed in the inspector for the TScrMemo so I added to the FormShow:
ScrMemo1.StyleElements:=[seFont,seBorder];
and the background still changes to the theme color. Tried FormCreate also, no joy.