--- a/gfx/layers/apz/src/APZCTreeManager.cpp
+++ b/gfx/layers/apz/src/APZCTreeManager.cpp
@@ -814,17 +814,18 @@ APZCTreeManager::ReceiveInputEvent(Input
           targetConfirmed = false;
         }
         result = mInputQueue->ReceiveInputEvent(
           apzc, targetConfirmed,
           mouseInput, aOutInputBlockId);
 
         // Under some conditions, we can confirm the drag block right away.
         // Otherwise, we have to wait for a main-thread confirmation.
-        if (apzDragEnabled && startsDrag && hitScrollbarNode &&
+        if (apzDragEnabled && gfxPrefs::APZDragInitiationEnabled() &&
+            startsDrag && hitScrollbarNode &&
             hitScrollbarNode->IsScrollThumbNode() &&
             hitScrollbarNode->GetScrollThumbData().mIsAsyncDraggable &&
             // check that the scrollbar's target scroll frame is layerized
             hitScrollbarNode->GetScrollTargetId() == apzc->GetGuid().mScrollId &&
             !apzc->IsScrollInfoLayer() && mInputQueue->GetCurrentDragBlock()) {
           uint64_t dragBlockId = mInputQueue->GetCurrentDragBlock()->GetBlockId();
           const ScrollThumbData& thumbData = hitScrollbarNode->GetScrollThumbData();
           // AsyncPanZoomController::HandleInputEvent() will call

--- a/gfx/thebes/gfxPrefs.h
+++ b/gfx/thebes/gfxPrefs.h
@@ -290,16 +290,17 @@ private:
   DECL_GFX_PREF(Live, "apz.axis_lock.lock_angle",              APZAxisLockAngle, float, float(M_PI / 6.0) /* 30 degrees */);
   DECL_GFX_PREF(Live, "apz.axis_lock.mode",                    APZAxisLockMode, int32_t, 0);
   DECL_GFX_PREF(Live, "apz.content_response_timeout",          APZContentResponseTimeout, int32_t, 400);
   DECL_GFX_PREF(Live, "apz.danger_zone_x",                     APZDangerZoneX, int32_t, 50);
   DECL_GFX_PREF(Live, "apz.danger_zone_y",                     APZDangerZoneY, int32_t, 100);
   DECL_GFX_PREF(Live, "apz.disable_for_scroll_linked_effects", APZDisableForScrollLinkedEffects, bool, false);
   DECL_GFX_PREF(Live, "apz.displayport_expiry_ms",             APZDisplayPortExpiryTime, uint32_t, 15000);
   DECL_GFX_PREF(Live, "apz.drag.enabled",                      APZDragEnabled, bool, false);
+  DECL_GFX_PREF(Live, "apz.drag.initial.enabled",              APZDragInitiationEnabled, bool, false);
   DECL_GFX_PREF(Live, "apz.enlarge_displayport_when_clipped",  APZEnlargeDisplayPortWhenClipped, bool, false);
   DECL_GFX_PREF(Live, "apz.fling_accel_base_mult",             APZFlingAccelBaseMultiplier, float, 1.0f);
   DECL_GFX_PREF(Live, "apz.fling_accel_interval_ms",           APZFlingAccelInterval, int32_t, 500);
   DECL_GFX_PREF(Live, "apz.fling_accel_supplemental_mult",     APZFlingAccelSupplementalMultiplier, float, 1.0f);
   DECL_GFX_PREF(Live, "apz.fling_accel_min_velocity",          APZFlingAccelMinVelocity, float, 1.5f);
   DECL_GFX_PREF(Once, "apz.fling_curve_function_x1",           APZCurveFunctionX1, float, 0.0f);
   DECL_GFX_PREF(Once, "apz.fling_curve_function_x2",           APZCurveFunctionX2, float, 1.0f);
   DECL_GFX_PREF(Once, "apz.fling_curve_function_y1",           APZCurveFunctionY1, float, 0.0f);

--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -643,18 +643,20 @@ pref("apz.allow_zooming", false);
 pref("apz.axis_lock.mode", 0);
 pref("apz.axis_lock.lock_angle", "0.5235987");        // PI / 6 (30 degrees)
 pref("apz.axis_lock.breakout_threshold", "0.03125");  // 1/32 inches
 pref("apz.axis_lock.breakout_angle", "0.3926991");    // PI / 8 (22.5 degrees)
 pref("apz.axis_lock.direct_pan_angle", "1.047197");   // PI / 3 (60 degrees)
 pref("apz.content_response_timeout", 400);
 #ifdef NIGHTLY_BUILD
 pref("apz.drag.enabled", true);
+pref("apz.drag.initial.enabled", true);
 #else
 pref("apz.drag.enabled", false);
+pref("apz.drag.initial.enabled", false);
 #endif
 pref("apz.danger_zone_x", 50);
 pref("apz.danger_zone_y", 100);
 pref("apz.disable_for_scroll_linked_effects", false);
 pref("apz.displayport_expiry_ms", 15000);
 pref("apz.enlarge_displayport_when_clipped", false);
 pref("apz.fling_accel_base_mult", "1.0");
 pref("apz.fling_accel_interval_ms", 500);