--- a/browser/actors/ContextMenuChild.jsm
+++ b/browser/actors/ContextMenuChild.jsm
@@ -701,16 +701,26 @@ class ContextMenuChild extends ActorChil
 
     if (node.nodeType == node.DOCUMENT_NODE ||
         // Don't display for XUL element unless <label class="text-link">
         (node.namespaceURI == XUL_NS && !this._isXULTextLinkLabel(node))) {
       context.shouldDisplay = false;
       return;
     }
 
+    const isAboutDevtoolsToolbox =
+          this.content.document.documentURI.startsWith("about:devtools-toolbox");
+    const editFlags = SpellCheckHelper.isEditable(node, this.content);
+
+    if (isAboutDevtoolsToolbox && (editFlags & SpellCheckHelper.TEXTINPUT) === 0) {
+      // Don't display for about:devtools-toolbox page unless the source was text input.
+      context.shouldDisplay = false;
+      return;
+    }
+
     // Initialize context to be sent to nsContextMenu
     // Keep this consistent with the similar code in nsContextMenu's setContext
     context.bgImageURL          = "";
     context.imageDescURL        = "";
     context.imageInfo           = null;
     context.mediaURL            = "";
     context.webExtBrowserType   = "";
 
@@ -759,26 +769,35 @@ class ContextMenuChild extends ActorChil
     context.frameOuterWindowID = WebNavigationFrames.getFrameId(context.target.ownerGlobal);
 
     // Check if we are in a synthetic document (stand alone image, video, etc.).
     context.inSyntheticDoc = context.target.ownerDocument.mozSyntheticDocument;
 
     context.shouldInitInlineSpellCheckerUINoChildren = false;
     context.shouldInitInlineSpellCheckerUIWithChildren = false;
 
-    let editFlags = SpellCheckHelper.isEditable(context.target, this.content);
     this._setContextForNodesNoChildren(editFlags);
     this._setContextForNodesWithChildren(editFlags);
 
     this.lastMenuTarget = {
       // Remember the node for extensions.
       targetRef: Cu.getWeakReference(node),
       // The timestamp is used to verify that the target wasn't changed since the observed menu event.
       timeStamp: context.timeStamp,
     };
+
+    if (isAboutDevtoolsToolbox) {
+      // Setup the menu items on text input in about:devtools-toolbox.
+      context.inAboutDevtoolsToolbox = true;
+      context.canSpellCheck = false;
+      context.inTabBrowser = false;
+      context.inFrame = false;
+      context.inSrcdocFrame = false;
+      context.onSpellcheckable = false;
+    }
   }
 
   /**
    * Sets up the parts of the context menu for when when nodes have no children.
    *
    * @param {Integer} editFlags The edit flags for the node. See SpellCheckHelper
    *                            for the details.
    */

--- a/browser/base/content/nsContextMenu.js
+++ b/browser/base/content/nsContextMenu.js
@@ -220,16 +220,18 @@ nsContextMenu.prototype = {
 
     this.target = this.isRemote ? context.target : document.popupNode;
     this.targetAsCPOW = context.targetAsCPOW;
 
     this.principal = context.principal;
     this.frameOuterWindowID = context.frameOuterWindowID;
 
     this.inSyntheticDoc = context.inSyntheticDoc;
+    this.inAboutDevtoolsToolbox = context.inAboutDevtoolsToolbox;
+
 
     // Everything after this isn't sent directly from ContextMenu
     this.ownerDoc = this.target.ownerDocument;
 
     // Remember the CSS selectors corresponding to clicked node. gContextMenuContentData
     // can be null if the menu was triggered by tests in which case use an empty array.
     this.targetSelectors = gContextMenuContentData
                            ? gContextMenuContentData.popupNodeSelectors
@@ -418,33 +420,24 @@ nsContextMenu.prototype = {
     let mediaIsBlob = this.mediaURL.startsWith("blob:");
     this.setItemAttr("context-sendvideo", "disabled", !this.mediaURL || mediaIsBlob);
     this.setItemAttr("context-sendaudio", "disabled", !this.mediaURL || mediaIsBlob);
   },
 
   initViewItems: function CM_initViewItems() {
     // View source is always OK, unless in directory listing.
     this.showItem("context-viewpartialsource-selection",
-                  this.isContentSelected);
-
-    const {gBrowser} = this.browser.ownerGlobal;
-    // Hide menu that opens devtools when the window is showing `about:devtools-toolbox`.
-    // This is to avoid displaying multiple devtools at the same time. See bug 1495944.
-    const isAboutDevtoolsToolbox = gBrowser &&
-                                   gBrowser.currentURI &&
-                                   gBrowser.currentURI.scheme === "about" &&
-                                   gBrowser.currentURI.filePath === "devtools-toolbox";
+                  !this.inAboutDevtoolsToolbox && this.isContentSelected);
 
     var shouldShow = !(this.isContentSelected ||
                        this.onImage || this.onCanvas ||
                        this.onVideo || this.onAudio ||
                        this.onLink || this.onTextInput);
 
-    var showInspect = this.inTabBrowser &&
-                      !isAboutDevtoolsToolbox &&
+    var showInspect = this.inTabBrowser && !this.inAboutDevtoolsToolbox &&
                       Services.prefs.getBoolPref("devtools.inspector.enabled", true) &&
                       !Services.prefs.getBoolPref("devtools.policy.disabled", false);
 
     var showInspectA11Y = showInspect &&
                           // Only when accessibility service started.
                           Services.appinfo.accessibilityEnabled &&
                           this.inTabBrowser &&
                           Services.prefs.getBoolPref("devtools.enabled", true) &&
@@ -522,17 +515,18 @@ nsContextMenu.prototype = {
                     this.onCanvas || this.inWebExtBrowser));
 
     this.showItem("context-bookmarklink", (this.onLink && !this.onMailtoLink &&
                                            !this.onMozExtLink) || this.onPlainTextLink);
     this.showItem("context-keywordfield",
                   this.onTextInput && this.onKeywordField);
     this.showItem("frame", this.inFrame);
 
-    let showSearchSelect = (this.isTextSelected || this.onLink) && !this.onImage;
+    let showSearchSelect = !this.inAboutDevtoolsToolbox &&
+                           (this.isTextSelected || this.onLink) && !this.onImage;
     this.showItem("context-searchselect", showSearchSelect);
     if (showSearchSelect) {
       this.formatSearchContextItem();
     }
 
     // srcdoc cannot be opened separately due to concerns about web
     // content with about:srcdoc in location bar masquerading as trusted
     // chrome/addon content.
@@ -623,17 +617,18 @@ nsContextMenu.prototype = {
                   this.isContentSelected || this.onTextInput);
     this.showItem("context-paste", this.onTextInput);
     this.showItem("context-delete", this.onTextInput);
     this.showItem("context-sep-paste", this.onTextInput);
     this.showItem("context-selectall", !(this.onLink || this.onImage ||
                                          this.onVideo || this.onAudio ||
                                          this.inSyntheticDoc) ||
                                        this.isDesignMode);
-    this.showItem("context-sep-selectall", this.isContentSelected );
+    this.showItem("context-sep-selectall",
+                  !this.inAboutDevtoolsToolbox && this.isContentSelected);
 
     // XXX dr
     // ------
     // nsDocumentViewer.cpp has code to determine whether we're
     // on a link or an image. we really ought to be using that...
 
     // Copy email link depends on whether we're on an email link.
     this.showItem("context-copyemail", this.onMailtoLink);

--- a/devtools/client/aboutdebugging-new/test/browser/browser_aboutdebugging_devtoolstoolbox_contextmenu.js
+++ b/devtools/client/aboutdebugging-new/test/browser/browser_aboutdebugging_devtoolstoolbox_contextmenu.js
@@ -27,25 +27,43 @@ add_task(async function() {
   info("Check whether the menu item which opens devtools is enabled");
   await assertContextMenu(rootDocument, devtoolsBrowser, "#mount", true);
 
   await closeAboutDevtoolsToolbox(devtoolsTab, window);
   await removeTab(tab);
 });
 
 async function assertContextMenu(rootDocument, browser, targetSelector, shouldBeEnabled) {
+  if (shouldBeEnabled) {
+    await assertContextMenuEnabled(rootDocument, browser, targetSelector);
+  } else {
+    await assertContextMenuDisabled(rootDocument, browser, targetSelector);
+  }
+}
+
+async function assertContextMenuDisabled(rootDocument, browser, targetSelector) {
+  const contextMenu = rootDocument.getElementById("contentAreaContextMenu");
+  let isPopupShown = false;
+  const listener = () => {
+    isPopupShown = true;
+  };
+  contextMenu.addEventListener("popupshown", listener);
+  BrowserTestUtils.synthesizeMouseAtCenter(targetSelector,
+                                           { type: "contextmenu" }, browser);
+  await wait(1000);
+  ok(!isPopupShown, `Context menu should not be shown`);
+  contextMenu.removeEventListener("popupshown", listener);
+}
+
+async function assertContextMenuEnabled(rootDocument, browser, targetSelector) {
   // Show content context menu.
   const contextMenu = rootDocument.getElementById("contentAreaContextMenu");
   const popupShownPromise = BrowserTestUtils.waitForEvent(contextMenu, "popupshown");
   BrowserTestUtils.synthesizeMouseAtCenter(targetSelector,
                                            { type: "contextmenu" }, browser);
   await popupShownPromise;
-
-  // Check hidden attribute of #context-inspect.
-  const inspectMenuItem = rootDocument.getElementById("context-inspect");
-  is(inspectMenuItem.hidden, !shouldBeEnabled,
-     '"hidden" attribute of #context-inspect should be correct');
+  ok(true, `Context menu should be shown`);
 
   // Hide content context menu.
   const popupHiddenPromise = BrowserTestUtils.waitForEvent(contextMenu, "popuphidden");
   contextMenu.hidePopup();
   await popupHiddenPromise;
 }