src/vs/editor/browser/widget/diffEditorWidget.ts/DiffEditorWidgetStyle/applyColors
class DiffEditorWidgetStyle:	public applyColors(theme: IColorTheme): boolean {
		const newInsertColor = theme.getColor(diffOverviewRulerInserted) || (theme.getColor(diffInserted) || defaultInsertColor).transparent(2);
		const newRemoveColor = theme.getColor(diffOverviewRulerRemoved) || (theme.getColor(diffRemoved) || defaultRemoveColor).transparent(2);
		const hasChanges = !newInsertColor.equals(this._insertColor) || !newRemoveColor.equals(this._removeColor);
		this._insertColor = newInsertColor;
		this._removeColor = newRemoveColor;
		return hasChanges;
	}