Introduce color_selectionmath

To have a distinctive color for selected math which works in both modes

Also, link color_selectionmath with QPalette::HighlightedText, so we
won't need to special-case on lyxrc.use_system_colors any longer

src/Color.cpp

@@ -264,6 +264,7 @@ ColorSet::ColorSet()
 	{ Color_background, N_("background"), "background", Linen, black, "background" },
 	{ Color_foreground, N_("text"), "foreground", black, Linen, "foreground" },
 	{ Color_selection, N_("selection"), "selection", "#add8e6", "#add8e6", "selection" },
+	{ Color_selectionmath, N_("selected math"), "selectionmath", "#00008B", "#00008B", "selectionmath" },
 	{ Color_selectiontext, N_("selected text"), "selectiontext", black, black, "selectiontext" },
 	{ Color_latex, N_("LaTeX text"), "latex", DarkRed, "#D66613", "latex" },
 	{ Color_textlabel1, N_("Text label 1"), "textlabel1", blue, "#86a4ff", "textlabel1" },

src/ColorCode.h

@@ -65,6 +65,8 @@ enum ColorCode {
 	Color_foreground,
 	/// Background color of selected text
 	Color_selection,
+	/// Foreground color of selected math
+	Color_selectionmath,
 	/// Foreground color of selected text
 	Color_selectiontext,
 	/// Text color in LaTeX mode

src/frontends/qt/ColorCache.cpp

@@ -45,6 +45,7 @@ QPalette::ColorRole role(ColorCode col)
 	case Color_selection:
 		return QPalette::Highlight;
 		break;
+	case Color_selectionmath:
 	case Color_selectiontext:
 		return QPalette::HighlightedText;
 		break;

src/mathed/InsetMathHull.cpp

@@ -697,8 +697,7 @@ void InsetMathHull::draw(PainterInfo & pi, int x, int y) const
 	}
 
 	// Then the equations
-	ColorCode color = pi.selected && lyxrc.use_system_colors
+	ColorCode color = pi.selected ? Color_selectionmath : standardColor();
-		? Color_selectiontext : standardColor();
 	bool const really_change_color = pi.base.font.color() == Color_none;
 	Changer dummy0 = really_change_color ? pi.base.font.changeColor(color)
 		: noChange();

src/mathed/MathRow.cpp

@@ -356,8 +356,7 @@ void MathRow::draw(PainterInfo & pi, int x, int const y) const
 			x += e.before + e.after;
 			break;
 		case BEGIN_SEL:
-			if (lyxrc.use_system_colors)
+			change_color = pi.base.font.changeColor(Color_selectionmath);
-				change_color = pi.base.font.changeColor(Color_selectiontext);
 			break;
 		case END_SEL:
 			change_color = noChange();