fix(live-preview): keep LP panel open after popout while in design mode

In design mode the LP panel fills the editor area, so hiding it on
popout left the user with an empty workspace. Skip _setPanelVisibility(false)
when in design mode and capture the decision before the async
openUrlInBrowser so both code paths agree even if design mode flips
mid-call. Outside design mode, the original close-panel behavior is
unchanged.

Author: abose

src/extensionsIntegrated/Phoenix-live-preview/main.js

@@ -675,12 +675,18 @@ define(function (require, exports, module) {
     function _popoutLivePreview(browserName) {
         // We cannot use $iframe.src here if panel is hidden
         const openURL = StaticServer.getTabPopoutURL(currentLivePreviewURL);
+        // In design mode the LP panel fills the editor area — hiding it would
+        // leave the user staring at a blank workspace. Keep the panel open and
+        // just open the popout alongside it.
+        const closePanelAfterPopout = !WorkspaceManager.isInDesignMode();
         if(browserName && ALLOWED_BROWSERS_NAMES.includes(browserName)){
             Metrics.countEvent(Metrics.EVENT_TYPE.LIVE_PREVIEW, "popout", browserName);
             NodeUtils.openUrlInBrowser(openURL, browserName)
                 .then(()=>{
                     _loadPreview(true);
-                    _setPanelVisibility(false);
+                    if (closePanelAfterPopout) {
+                        _setPanelVisibility(false);
+                    }
                 })
                 .catch(err=>{
                     console.error("Error opening url in browser: ", browserName, err);
@@ -695,7 +701,9 @@ define(function (require, exports, module) {
             NativeApp.openURLInDefaultBrowser(openURL, "livePreview");
             Metrics.countEvent(Metrics.EVENT_TYPE.LIVE_PREVIEW, "popoutBtn", "click");
             _loadPreview(true);
-            _setPanelVisibility(false);
+            if (closePanelAfterPopout) {
+                _setPanelVisibility(false);
+            }
         }
     }