diff --git a/src/visualizers/FactorFence.ts b/src/visualizers/FactorFence.ts
index 894dd33c..21780d98 100644
--- a/src/visualizers/FactorFence.ts
+++ b/src/visualizers/FactorFence.ts
@@ -359,9 +359,6 @@ class FactorFence extends P5Visualizer(paramDesc) {
         // no stroke (rectangles without borders)
         this.sketch.strokeWeight(0)
         this.sketch.frameRate(30)
-
-        // Only need a couple of frames to start with:
-        this.stop(tryFrames)
     }
 
     /** md
@@ -372,6 +369,29 @@ term that the mouse is above. Clicking a prime will set it as the persistent
 highlight value. You can drag the chart in any direction to pan the view.
 
     **/
+    // Implementation notes: control events (keypresses and mouse gestures) are
+    // handled in this code in a slightly roundabout way: every draw() call
+    // checks whether a keypress is in effect and/or whether any mouse
+    // gestures are occurring, and handles them accordingly. But since the
+    // graph doesn't change except as a result of these actions (or the cache
+    // filling), the draw loop can generally stop. So the interaction checkers
+    // have to extend the draw loop if they fire. And then finally, since
+    // the draw loop tends to stop, pretty much all that the actual
+    // event-handling functions (mousePressed() etc, well below here in this
+    // file) have to do is restart the draw loop, and then the interaction
+    // checkers in draw() will actually implement the behaviors that should
+    // be invoked by those events.
+    // It might be more natural-seeming to implement the behaviors directly
+    // in the event-handling functions. That simpler scheme would likely work
+    // for the mouse events. However, it is unclear how, in that scheme, one
+    // could implement the behavior that the graph continues to zoom (or
+    // stretch or whatever) as you hold the corresponding key down. That's
+    // because you can only rely on a single keyPressed() event and a single
+    // keyReleased() event, no matter how long you hold a key down.
+    // So something has to run in the meantime and check if the key is still
+    // down, and it seems as though that has to be the draw() call. And
+    // as long as the draw() call is implementing the key controls, it seems
+    // that for consistency, it might as well do all the controls.
     mouseCheckDrag() {
         const movement = new p5.Vector(this.sketch.mouseX, this.sketch.mouseY)
         movement.sub(this.dragStart)
@@ -381,6 +401,7 @@ highlight value. You can drag the chart in any direction to pan the view.
             this.dragging = true
             movement.mult(1 / this.scaleFactor)
             this.graphCorner = this.graphCornerStart.copy().add(movement)
+            this.extendLoop()
         }
     }
 
@@ -404,37 +425,36 @@ In addition, several keypress commands are recognized:
                 : 0.97
             this.scaleFactor *= keyScale
             this.graphCorner.y = this.graphCorner.y / keyScale
-        }
-        /** md
+        } else if (this.sketch.keyIsDown(this.sketch.UP_ARROW)) {
+            /** md
 - up and down arrow: stretch the bars vertically
-        **/
-        if (this.sketch.keyIsDown(this.sketch.UP_ARROW)) {
+             **/
             // stretch up UP
             this.heightScale *= 1.03
-        }
-        if (this.sketch.keyIsDown(this.sketch.DOWN_ARROW)) {
+        } else if (this.sketch.keyIsDown(this.sketch.DOWN_ARROW)) {
             // contract down DOWN
             this.heightScale *= 0.97
-        }
-        /** md
+        } else if (this.sketch.keyIsDown(74)) {
+            /** md
 - J/I/K/L: pan the chart left/up/down/right
-        **/
-        if (this.sketch.keyIsDown(74)) {
+             **/
             // pan left J
             this.graphCorner.x -= 10 / this.scaleFactor
-        }
-        if (this.sketch.keyIsDown(76)) {
+        } else if (this.sketch.keyIsDown(76)) {
             // pan right L
             this.graphCorner.x += 10 / this.scaleFactor
-        }
-        if (this.sketch.keyIsDown(73)) {
+        } else if (this.sketch.keyIsDown(73)) {
             // pan up I
             this.graphCorner.y -= 10 / this.scaleFactor
-        }
-        if (this.sketch.keyIsDown(75)) {
+        } else if (this.sketch.keyIsDown(75)) {
             // pan down K
             this.graphCorner.y += 10 / this.scaleFactor
+        } else {
+            // no key we care about
+            return
         }
+        // Make sure that if we keep the key down, the drawing keeps adjusting:
+        this.extendLoop()
     }
 
     draw() {
@@ -516,6 +536,8 @@ In addition, several keypress commands are recognized:
         // If we are waiting on elements or factorizations, extend lifetime
         if (this.collectFailed || this.firstFailure < barsInfo.maxBars) {
             this.extendLoop()
+        } else {
+            this.stop(tryFrames)
         }
     }
 
@@ -677,12 +699,17 @@ In addition, several keypress commands are recognized:
         this.extendLoop()
     }
 
+    mouseDragged(event: MouseEvent) {
+        this.mouseLast = event
+        this.extendLoop()
+    }
+
     mousePressed() {
         if (!this.mouseOnSketch()) return
         this.mouseDown = true
         this.dragStart = new p5.Vector(this.sketch.mouseX, this.sketch.mouseY)
         this.graphCornerStart = this.graphCorner.copy()
-        this.continue()
+        this.extendLoop()
     }
 
     mouseReleased() {
diff --git a/src/visualizers/P5Visualizer.ts b/src/visualizers/P5Visualizer.ts
index 4eedccc5..0180f04f 100644
--- a/src/visualizers/P5Visualizer.ts
+++ b/src/visualizers/P5Visualizer.ts
@@ -191,7 +191,11 @@ export function P5Visualizer<PD extends GenericParamDescription>(desc: PD) {
                         ) {
                             sketch[method] = (event: KeyboardEvent) => {
                                 const active = document.activeElement
-                                if (active && active.tagName === 'INPUT') {
+                                if (
+                                    active
+                                    && (active.tagName === 'INPUT'
+                                        || active.tagName === 'TEXTAREA')
+                                ) {
                                     return true
                                 }
                                 return this[method](event)