Reposition popup on window resize rather than clear the search

Fixes #107

ext/fg/js/frontend.js

@@ -139,8 +139,14 @@ class Frontend {
         }
     }
 
-    onResize() {
-        this.searchClear(false);
+    async onResize() {
+        if (this.textSourceLast !== null && await this.popup.isVisibleAsync()) {
+            const textSource = this.textSourceLast;
+            this.lastShowPromise = this.popup.showContent(
+                textSource.getRect(),
+                textSource.getWritingMode()
+            );
+        }
     }
 
     onClick(e) {

ext/fg/js/popup-proxy-host.js

@@ -40,6 +40,7 @@ class PopupProxyHost {
             createNestedPopup: ({parentId}) => this.createNestedPopup(parentId),
             setOptions: ({id, options}) => this.setOptions(id, options),
             hide: ({id, changeFocus}) => this.hide(id, changeFocus),
+            isVisibleAsync: ({id}) => this.isVisibleAsync(id),
             setVisibleOverride: ({id, visible}) => this.setVisibleOverride(id, visible),
             containsPoint: ({id, x, y}) => this.containsPoint(id, x, y),
             showContent: ({id, elementRect, writingMode, type, details}) => this.showContent(id, elementRect, writingMode, type, details),
@@ -97,9 +98,14 @@ class PopupProxyHost {
         return popup.hide(changeFocus);
     }
 
+    async isVisibleAsync(id) {
+        const popup = this.getPopup(id);
+        return await popup.isVisibleAsync();
+    }
+
     async setVisibleOverride(id, visible) {
         const popup = this.getPopup(id);
-        return popup.setVisibleOverride(visible);
+        return await popup.setVisibleOverride(visible);
     }
 
     async containsPoint(id, x, y) {

ext/fg/js/popup-proxy.js

@@ -58,6 +58,11 @@ class PopupProxy {
         return await this.invokeHostApi('hide', {id: this.id, changeFocus});
     }
 
+    async isVisibleAsync() {
+        const id = await this.getPopupId();
+        return await this.invokeHostApi('isVisibleAsync', {id});
+    }
+
     async setVisibleOverride(visible) {
         const id = await this.getPopupId();
         return await this.invokeHostApi('setVisibleOverride', {id, visible});

ext/fg/js/popup.js

@@ -239,6 +239,10 @@ class Popup {
         }
     }
 
+    async isVisibleAsync() {
+        return this.isVisible();
+    }
+
     isVisible() {
         return this.isInjected && (this.visibleOverride !== null ? this.visibleOverride : this.visible);
     }