Fix Popup positioning (#1095)

* Fix _fitPopup of a Popup.

* rush change

* Fix tests

(cherry picked from commit 091ea17)

common/changes/@itwin/core-react/fix-widgets-popup_2024-11-04-17-06.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@itwin/core-react",
+      "comment": "Fix Popup to adjust final position based on container size instead of window size.",
+      "type": "none"
+    }
+  ],
+  "packageName": "@itwin/core-react"
+}

ui/core-react/src/core-react/popup/Popup.tsx

@@ -579,16 +579,16 @@ export class Popup extends React.Component<PopupProps, PopupState> {
       return fittedPoint;
     }
 
-    // const popupRect = this._popup.getBoundingClientRect();
     const { popupWidth, popupHeight } = this._getPopupDimensions();
-    const { innerWidth, innerHeight } = window;
+    const container = this.getContainer();
+    const containerBounds = container.getBoundingClientRect();
 
-    if (fittedPoint.y + popupHeight > innerHeight) {
-      fittedPoint.y = innerHeight - popupHeight;
+    if (fittedPoint.y + popupHeight > containerBounds.height) {
+      fittedPoint.y = containerBounds.height - popupHeight;
     }
 
-    if (fittedPoint.x + popupWidth > innerWidth) {
-      fittedPoint.x = innerWidth - popupWidth;
+    if (fittedPoint.x + popupWidth > containerBounds.width) {
+      fittedPoint.x = containerBounds.width - popupWidth;
     }
 
     if (fittedPoint.y < 0) {

ui/core-react/src/test/popup/Popup.test.tsx

@@ -494,6 +494,9 @@ describe("<Popup />", () => {
       vi.spyOn(targetElement, "getBoundingClientRect").mockReturnValue(
         DOMRect.fromRect({ x: 100, y: 100, height: 50, width: 50 })
       );
+      vi.spyOn(document.body, "getBoundingClientRect").mockReturnValue(
+        DOMRect.fromRect({ x: 0, y: 0, width: 1000, height: 1000 })
+      );
     });
 
     afterEach(() => {