this addresses 44f1a61c42 (commitcomment-11015041)

src/js/contentscript-end.js

@@ -153,24 +153,6 @@ var collapser = (function() {
     var newRequests = [];
     var pendingRequests = {};
     var pendingRequestCount = 0;
-    var backgroundImage = [
-        'linear-gradient(',
-            '0deg,',
-            'rgba(0,0,0,0.02) 25%,',
-            'rgba(0,0,0,0.05) 25%,',
-            'rgba(0,0,0,0.05) 75%,',
-            'rgba(0,0,0,0.02) 75%,',
-            'rgba(0,0,0,0.02)',
-        ') center center / 10px 10px repeat scroll,',
-        'linear-gradient(',
-            '90deg,',
-            'rgba(0,0,0,0.02) 25%,',
-            'rgba(0,0,0,0.05) 25%,',
-            'rgba(0,0,0,0.05) 75%,',
-            'rgba(0,0,0,0.02) 75%,',
-            'rgba(0,0,0,0.02)',
-        ') center center / 10px 10px repeat scroll'
-    ].join('');
     var srcProps = {
         'iframe': 'src',
         'img': 'src'
@@ -205,7 +187,7 @@ var collapser = (function() {
             return;
         }
         var collapse = response.collapse;
-        var bgImg = backgroundImage;
+        var bgImg = response.backgroundImage;
         var i = requests.length;
         var request, entry, target, tagName;
         while ( i-- ) {

src/js/messaging.js

@@ -509,6 +509,9 @@ var onMessage = function(request, sender, callback) {
             collapse: µm.userSettings.collapseBlocked,
             requests: evaluateURLs(tabId, request.requests)
         };
+        if ( !response.collapse ) {
+            response.backgroundImage = vAPI.localStorage.getItem('placeholderBackgroundImage');
+        }
         break;
 
     case 'getUserAgentReplaceStr':

src/js/start.js

@@ -44,17 +44,8 @@ var µm = µMatrix;
 
 /******************************************************************************/
 
-var onAllDone = function() {
-    µm.webRequest.start();
-
-    // https://github.com/chrisaljoudi/uBlock/issues/184
-    // Check for updates not too far in the future.
-    µm.assetUpdater.onStart.addListener(µm.updateStartHandler.bind(µm));
-    µm.assetUpdater.onCompleted.addListener(µm.updateCompleteHandler.bind(µm));
-    µm.assetUpdater.onAssetUpdated.addListener(µm.assetUpdatedHandler.bind(µm));
-    µm.assets.onAssetCacheRemoved.addListener(µm.assetCacheRemovedHandler.bind(µm));
-
 // Browser data jobs
+
 var jobCallback = function() {
     if ( !µm.userSettings.clearBrowserCache ) {
         return;
@@ -69,11 +60,43 @@ var onAllDone = function() {
     // console.debug('clearBrowserCacheCallback()> vAPI.browserCache.clearByTime() called');
 };
 
+/******************************************************************************/
+
+var onAllDone = function() {
+    µm.webRequest.start();
+
+    // https://github.com/chrisaljoudi/uBlock/issues/184
+    // Check for updates not too far in the future.
+    µm.assetUpdater.onStart.addListener(µm.updateStartHandler.bind(µm));
+    µm.assetUpdater.onCompleted.addListener(µm.updateCompleteHandler.bind(µm));
+    µm.assetUpdater.onAssetUpdated.addListener(µm.assetUpdatedHandler.bind(µm));
+    µm.assets.onAssetCacheRemoved.addListener(µm.assetCacheRemovedHandler.bind(µm));
+
     µMatrix.asyncJobs.add('clearBrowserCache', null, jobCallback, 15 * 60 * 1000, true);
 
     // Important: remove barrier to remote fetching, this was useful only
     // for launch time.
     µm.assets.remoteFetchBarrier -= 1;
+
+    if ( vAPI.localStorage.getItem('placeholderBackgroundImage') === null ) {
+        vAPI.localStorage.setItem('placeholderBackgroundImage', [
+            'linear-gradient(0deg,',
+                'rgba(0,0,0,0.02) 25%,',
+                'rgba(0,0,0,0.05) 25%,',
+                'rgba(0,0,0,0.05) 75%,',
+                'rgba(0,0,0,0.02) 75%,',
+                'rgba(0,0,0,0.02)',
+            ') center center / 10px 10px repeat scroll,',
+            'linear-gradient(',
+                '90deg,',
+                'rgba(0,0,0,0.02) 25%,',
+                'rgba(0,0,0,0.05) 25%,',
+                'rgba(0,0,0,0.05) 75%,',
+                'rgba(0,0,0,0.02) 75%,',
+                'rgba(0,0,0,0.02)',
+            ') center center / 10px 10px repeat scroll'
+        ].join(''));
+    }
 };
 
 var onTabsReady = function(tabs) {