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.