diff --git a/dev/examples/gaia.js b/dev/examples/gaia.js
index 6372a480a..95e8cf2a1 100644
--- a/dev/examples/gaia.js
+++ b/dev/examples/gaia.js
@@ -45,7 +45,7 @@ export default async function(el) {
             from(table, { filterBy: brush }),
             { x: 'u', y: 'v', fill: 'density', bandwidth, binType, binWidth }
           ),
-          intervalXY({ as: brush, pixelSize }),
+          intervalXY({ as: brush, pixelSize, activateOn: 'mousedown' }),
           domainXY(Fixed),
           scaleColor('sqrt'), schemeColor('viridis'),
           width(700), height(400), marginLeft(25), marginTop(20), marginRight(1)
@@ -57,7 +57,7 @@ export default async function(el) {
               { x: bin('phot_g_mean_mag'), y: count(), fill: 'steelblue', inset: 0.5 }
             ),
             scaleY(histScale), gridY(true),
-            intervalX({ as: brush }), domainX(Fixed),
+            intervalX({ as: brush, activateOn: 'mousedown' }), domainX(Fixed),
             width(350), height(200), marginLeft(65)
           ),
           plot(
@@ -66,7 +66,7 @@ export default async function(el) {
               { x: bin('parallax'), y: count(), fill: 'steelblue', inset: 0.5 }
             ),
             scaleY(histScale), gridY(true),
-            intervalX({ as: brush }), domainX(Fixed),
+            intervalX({ as: brush, activateOn: 'mousedown' }), domainX(Fixed),
             width(350), height(200), marginLeft(65)
           )
         )
@@ -78,7 +78,7 @@ export default async function(el) {
           { x: 'bp_rp', y: 'phot_g_mean_mag', fill: 'density', bandwidth, binType, binWidth }
         ),
         scaleColor('sqrt'), schemeColor('viridis'), reverseY(true),
-        intervalXY({ as: brush, pixelSize }), domainXY(Fixed),
+        intervalXY({ as: brush, pixelSize, activateOn: 'mousedown' }), domainXY(Fixed),
         width(400), height(600), marginLeft(25), marginTop(20), marginRight(1)
       )
     )
diff --git a/dev/specs/gaia.yaml b/dev/specs/gaia.yaml
index 973ed6b3c..bb3d54205 100644
--- a/dev/specs/gaia.yaml
+++ b/dev/specs/gaia.yaml
@@ -36,6 +36,7 @@ hconcat:
     - select: intervalXY
       pixelSize: 2
       as: $brush
+      activateOn: mousedown
     domainXY: Fixed
     scaleColor: $scaleType
     schemeColor: viridis
@@ -54,6 +55,7 @@ hconcat:
         inset: 0.5
       - select: intervalX
         as: $brush
+        activateOn: mousedown
       domainX: Fixed
       scaleY: $scaleType
       gridY: true
@@ -69,6 +71,7 @@ hconcat:
         inset: 0.5
       - select: intervalX
         as: $brush
+        activateOn: mousedown
       domainX: Fixed
       scaleY: $scaleType
       gridY: true
@@ -88,6 +91,7 @@ hconcat:
   - select: intervalXY
     pixelSize: 2
     as: $brush
+    activateOn: mousedown
   domainXY: Fixed
   scaleColor: $scaleType
   schemeColor: viridis
diff --git a/packages/vgplot/src/interactors/Interval1D.js b/packages/vgplot/src/interactors/Interval1D.js
index dd5f92bad..cd53f9db2 100644
--- a/packages/vgplot/src/interactors/Interval1D.js
+++ b/packages/vgplot/src/interactors/Interval1D.js
@@ -12,7 +12,8 @@ export class Interval1D {
     field,
     pixelSize = 1,
     peers = true,
-    brush: style
+    brush: style,
+    activateOn = 'mouseenter'
   }) {
     this.mark = mark;
     this.channel = channel;
@@ -24,6 +25,7 @@ export class Interval1D {
     this.style = style && sanitizeStyles(style);
     this.brush = channel === 'y' ? brushY() : brushX();
     this.brush.on('brush end', ({ selection }) => this.publish(selection));
+    this.activateOn = activateOn;
   }
 
   activate() {
@@ -79,6 +81,6 @@ export class Interval1D {
       }
     }
 
-    svg.addEventListener('mouseenter', () => this.activate());
+    svg.addEventListener(this.activateOn, () => this.activate());
   }
 }
diff --git a/packages/vgplot/src/interactors/Interval2D.js b/packages/vgplot/src/interactors/Interval2D.js
index 7bb4275d7..69af2494b 100644
--- a/packages/vgplot/src/interactors/Interval2D.js
+++ b/packages/vgplot/src/interactors/Interval2D.js
@@ -14,7 +14,8 @@ export class Interval2D {
     yfield,
     pixelSize = 1,
     peers = true,
-    brush: style
+    brush: style,
+    activateOn = 'mouseenter'
   }) {
     this.mark = mark;
     this.pixelSize = pixelSize || 1;
@@ -25,6 +26,7 @@ export class Interval2D {
     this.style = style && sanitizeStyles(style);
     this.brush = brush();
     this.brush.on('brush end', ({ selection }) => this.publish(selection));
+    this.activateOn = activateOn;
   }
 
   activate() {
@@ -90,6 +92,6 @@ export class Interval2D {
       this.g.call(brush.move, [[x1, y1], [x2, y2]]);
     }
 
-    svg.addEventListener('mouseenter', () => this.activate());
+    svg.addEventListener(this.activateOn, () => this.activate());
   }
 }