For Patti LuPone, it was “the day from hell, all day.”  At Wednesday’s matinee of the Douglas Carter Beane comedy “Shows for Days,” in which Ms. LuPone plays a small-town theater diva, four cellphones went off, twice from the same phone. It created, as Ms. LuPone put it, “a cacophony of noise.”  So Ms. LuPone was on edge by the evening performance at the Mitzi E. Newhouse Theater. And when the woman seated at the end of the second row texted — and texted and texted — during the show, Ms. LuPone took action. Without breaking character, Ms. LuPone walked into the audience and took the woman’s phone. “She didn’t know what was going on,” Ms. LuPone said in a phone interview on Thursday. “I should be a sleight of hand artist.” (The phone was returned after the show.)  The incident comes on the heels of recent theatrical breaches of audience conduct at “Hand to God,” on Broadway (for an incursion onto the set), and “Hamilton” (for texting) at the Public Theater. Still reeling from Wednesday’s events, Ms. LuPone — who stopped a performance of “Gypsy” in 2009 to berate someone who was taking photographs — talked about the frustration of having to police theatrical etiquette. Following are edited excerpts from the conversation.  Q. So what happened Wednesday night?  A. This woman — a very pretty young woman — was sitting with her boyfriend or husband. We could see her text. She was so uninterested. She showed her husband what she was texting. We talked about it at intermission. When we went out for the second act I was very close to her, and she was still texting. I watched her and thought, “What am I going to do?” At the very end of that scene, we all exit. What I normally do is shake the hand of the people in the front row. I just walked over to her, shook her hand and took her phone. I walked offstage and handed it to the stage manager, who gave it to the house manager.  Q. How did the rest of the cast react?  A. Everybody is deeply upset by it. How can you not be distressed by this? Everybody is freaked out.  Q. If you could see it, then the rest of the audience probably could, too. It takes one screen to disrupt an entire theater.  A. I don’t know why they buy the ticket or come to the theater if they can’t let go of the phone. It’s controlling them. They can’t turn it off and can’t stop looking at it. They are truly inconsiderate, self-absorbed people who have no public manners whatsoever. I don’t know what to do anymore. I was hired as an actor, not a policeman of the audience.  Q. How did the audience react when you took her phone?  A. They got it. She was totally seen texting because she was in light. Some people gasped when I took the phone. Some people applauded.  Q. In a statement you released you said, “I am so defeated by this issue that I seriously question whether I want to work onstage anymore.” Is that true?  A. Absolutely. It’s getting worse. I’m hired to tell a story, and it takes a lot of effort and work to do that convincingly. It’s a handful of people who destroy that experience for everyone. It’s heartbreaking. Theater is not a social event.  A version of this article appears in print on July 10, 2015, on page C5 of the New York edition with the headline: Taking Matters Into Her Own Hand. Order Reprints| Today's Paper|Subscribe
Ms. LuPone talks about taking away the cellphone of a texting audience member during a performance of “Shows for Days.”