webapp: let copy operation write to clipboard (if allowed)
webapp: let copy operation write to clipboard (if allowed)

tscholl2/smc,DrXyzzy/smc,sagemathinc/smc,DrXyzzy/smc,DrXyzzy/smc,sagemathinc/smc,tscholl2/smc,tscholl2/smc,sagemathinc/smc,DrXyzzy/smc,tscholl2/smc,tscholl2/smc,sagemathinc/smc