--- a/devtools/client/debugger/content/views/sources-view.js
+++ b/devtools/client/debugger/content/views/sources-view.js
@@ -61,16 +61,17 @@ function SourcesView(controller, Debugge
   this._onBreakpointCheckboxClick = this._onBreakpointCheckboxClick.bind(this);
   this._onConditionalPopupShowing = this._onConditionalPopupShowing.bind(this);
   this._onConditionalPopupShown = this._onConditionalPopupShown.bind(this);
   this._onConditionalPopupHiding = this._onConditionalPopupHiding.bind(this);
   this._onConditionalTextboxKeyPress = this._onConditionalTextboxKeyPress.bind(this);
   this._onEditorContextMenuOpen = this._onEditorContextMenuOpen.bind(this);
   this._onCopyUrlCommand = this._onCopyUrlCommand.bind(this);
   this._onNewTabCommand = this._onNewTabCommand.bind(this);
+  this._onConditionalPopupHidden = this._onConditionalPopupHidden.bind(this);
 }
 
 SourcesView.prototype = Heritage.extend(WidgetMethods, {
   /**
    * Initialization function, called when the debugger is started.
    */
   initialize: function() {
     dumpn("Initializing the SourcesView");
@@ -108,20 +109,22 @@ SourcesView.prototype = Heritage.extend(
     this._editorContainer.addEventListener("mousedown", this._onMouseDown, false);
 
     this.widget.addEventListener("select", this._onSourceSelect, false);
 
     this._stopBlackBoxButton.addEventListener("click", this._onStopBlackBoxing, false);
     this._cbPanel.addEventListener("popupshowing", this._onConditionalPopupShowing, false);
     this._cbPanel.addEventListener("popupshown", this._onConditionalPopupShown, false);
     this._cbPanel.addEventListener("popuphiding", this._onConditionalPopupHiding, false);
+    this._cbPanel.addEventListener("popuphidden", this._onConditionalPopupHidden, false);
     this._cbTextbox.addEventListener("keypress", this._onConditionalTextboxKeyPress, false);
     this._copyUrlMenuItem.addEventListener("command", this._onCopyUrlCommand, false);
     this._newTabMenuItem.addEventListener("command", this._onNewTabCommand, false);
 
+    this._cbPanel.hidden = true;
     this.allowFocusOnRightClick = true;
     this.autoFocusOnSelection = false;
     this.autoFocusOnFirstItem = false;
 
     // Sort the contents by the displayed label.
     this.sortContents((aFirst, aSecond) => {
       return +(aFirst.attachment.label.toLowerCase() >
                aSecond.attachment.label.toLowerCase());
@@ -146,16 +149,17 @@ SourcesView.prototype = Heritage.extend(
   destroy: function() {
     dumpn("Destroying the SourcesView");
 
     this.widget.removeEventListener("select", this._onSourceSelect, false);
     this._stopBlackBoxButton.removeEventListener("click", this._onStopBlackBoxing, false);
     this._cbPanel.removeEventListener("popupshowing", this._onConditionalPopupShowing, false);
     this._cbPanel.removeEventListener("popupshown", this._onConditionalPopupShown, false);
     this._cbPanel.removeEventListener("popuphiding", this._onConditionalPopupHiding, false);
+    this._cbPanel.removeEventListener("popuphidden", this._onConditionalPopupHidden, false);
     this._cbTextbox.removeEventListener("keypress", this._onConditionalTextboxKeyPress, false);
     this._copyUrlMenuItem.removeEventListener("command", this._onCopyUrlCommand, false);
     this._newTabMenuItem.removeEventListener("command", this._onNewTabCommand, false);
     this.DebuggerView.editor.off("popupOpen", this._onEditorContextMenuOpen, false);
   },
 
   empty: function() {
     WidgetMethods.empty.call(this);
@@ -672,36 +676,47 @@ SourcesView.prototype = Heritage.extend(
    */
   _openConditionalPopup: function() {
     let breakpointItem = this._getBreakpoint(this._selectedBreakpoint);
     let attachment = breakpointItem.attachment;
     // Check if this is an enabled conditional breakpoint, and if so,
     // retrieve the current conditional epression.
     let bp = getBreakpoint(this.getState(), attachment);
     let expr = (bp ? (bp.condition || "") : "");
+    let cbPanel = this._cbPanel;
 
     // Update the conditional expression textbox. If no expression was
     // previously set, revert to using an empty string by default.
     this._cbTextbox.value = expr;
 
-    // Show the conditional expression panel. The popup arrow should be pointing
-    // at the line number node in the breakpoint item view.
-    this._cbPanel.hidden = false;
-    this._cbPanel.openPopup(breakpointItem.attachment.view.lineNumber,
-                            BREAKPOINT_CONDITIONAL_POPUP_POSITION,
-                            BREAKPOINT_CONDITIONAL_POPUP_OFFSET_X,
-                            BREAKPOINT_CONDITIONAL_POPUP_OFFSET_Y);
+
+    function openPopup() {
+      // Show the conditional expression panel. The popup arrow should be pointing
+      // at the line number node in the breakpoint item view.
+      cbPanel.hidden = false;
+      cbPanel.openPopup(breakpointItem.attachment.view.lineNumber,
+                              BREAKPOINT_CONDITIONAL_POPUP_POSITION,
+                              BREAKPOINT_CONDITIONAL_POPUP_OFFSET_X,
+                              BREAKPOINT_CONDITIONAL_POPUP_OFFSET_Y);
+
+      cbPanel.removeEventListener('popuphidden', openPopup, false);
+    }
+
+    // Wait until the other cb panel is closed
+    if (!this._cbPanel.hidden) {
+      this._cbPanel.addEventListener('popuphidden', openPopup, false);
+    } else {
+      openPopup();
+    }
   },
 
   /**
    * Hides a conditional breakpoint's expression input popup.
    */
   _hideConditionalPopup: function() {
-    this._cbPanel.hidden = true;
-
     // Sometimes this._cbPanel doesn't have hidePopup method which doesn't
     // break anything but simply outputs an exception to the console.
     if (this._cbPanel.hidePopup) {
       this._cbPanel.hidePopup();
     }
   },
 
   /**
@@ -1168,16 +1183,23 @@ SourcesView.prototype = Heritage.extend(
     let bp = this._selectedBreakpoint;
     if (bp) {
       let condition = this._cbTextbox.value;
       this.actions.setBreakpointCondition(bp.location, condition);
     }
   },
 
   /**
+   * The popup hidden listener for the breakpoints conditional expression panel.
+   */
+  _onConditionalPopupHidden: function() {
+    this._cbPanel.hidden = true;
+  },
+
+  /**
    * The keypress listener for the breakpoints conditional expression textbox.
    */
   _onConditionalTextboxKeyPress: function(e) {
     if (e.keyCode == e.DOM_VK_RETURN) {
       this._hideConditionalPopup();
     }
   },