src/vs/workbench/browser/parts/views/viewPane.ts/ViewPane/style
class ViewPane:	override style(styles: IPaneStyles): void {
		super.style(styles);

		const icon = this.getIcon();
		if (this.iconContainer) {
			const fgColor = styles.headerForeground || this.themeService.getColorTheme().getColor(foreground);
			if (URI.isUri(icon)) {
				// Apply background color to activity bar item provided with iconUrls
				this.iconContainer.style.backgroundColor = fgColor ? fgColor.toString() : '';
				this.iconContainer.style.color = '';
			} else {
				// Apply foreground color to activity bar items provided with codicons
				this.iconContainer.style.color = fgColor ? fgColor.toString() : '';
				this.iconContainer.style.backgroundColor = '';
			}
		}
	}