yubing24

<mat-toolbar color="accent">
    <button mat-icon-button matTooltip="Application Menu" (click)="sidenav.toggle()">
        <mat-icon>settings</mat-icon>
    </button>
    Account Settings
    <span style="flex: 1 1 auto;"></span>
    <div>
        <button mat-icon-button matTooltip="Switch Apps">
            <mat-icon>apps</mat-icon>
        </button>