Fix emoji picker and stickerpicker not appearing correctly when opened

src/components/structures/ContextMenu.tsx

@@ -322,10 +322,16 @@ export class ContextMenu extends React.PureComponent<IProps, IState> {
 
         const menuClasses = classNames({
             'mx_ContextualMenu': true,
-            'mx_ContextualMenu_left': !hasChevron && position.left,
-            'mx_ContextualMenu_right': !hasChevron && position.right,
-            'mx_ContextualMenu_top': !hasChevron && position.top,
-            'mx_ContextualMenu_bottom': !hasChevron && position.bottom,
+            /**
+             * In some cases we may get the number of 0, which still means that we're supposed to properly
+             * add the specific position class, but as it was falsy things didn't work as intended.
+             * In addition, defensively check for counter cases where we may get more than one value,
+             * even if we shouldn't.
+             */
+            'mx_ContextualMenu_left': !hasChevron && position.left !== undefined && !position.right,
+            'mx_ContextualMenu_right': !hasChevron && position.right !== undefined && !position.left,
+            'mx_ContextualMenu_top': !hasChevron && position.top !== undefined && !position.bottom,
+            'mx_ContextualMenu_bottom': !hasChevron && position.bottom !== undefined && !position.top,
             'mx_ContextualMenu_withChevron_left': chevronFace === ChevronFace.Left,
             'mx_ContextualMenu_withChevron_right': chevronFace === ChevronFace.Right,
             'mx_ContextualMenu_withChevron_top': chevronFace === ChevronFace.Top,
@@ -404,17 +410,27 @@ export class ContextMenu extends React.PureComponent<IProps, IState> {
     }
 }
 
+export type ToRightOf = {
+    left: number;
+    top: number;
+    chevronOffset: number;
+};
+
 // Placement method for <ContextMenu /> to position context menu to right of elementRect with chevronOffset
-export const toRightOf = (elementRect: Pick<DOMRect, "right" | "top" | "height">, chevronOffset = 12) => {
+export const toRightOf = (elementRect: Pick<DOMRect, "right" | "top" | "height">, chevronOffset = 12): ToRightOf => {
     const left = elementRect.right + window.pageXOffset + 3;
     let top = elementRect.top + (elementRect.height / 2) + window.pageYOffset;
     top -= chevronOffset + 8; // where 8 is half the height of the chevron
     return { left, top, chevronOffset };
 };
 
+export type AboveLeftOf = IPosition & {
+    chevronFace: ChevronFace;
+};
+
 // Placement method for <ContextMenu /> to position context menu right-aligned and flowing to the left of elementRect,
 // and either above or below: wherever there is more space (maybe this should be aboveOrBelowLeftOf?)
-export const aboveLeftOf = (elementRect: DOMRect, chevronFace = ChevronFace.None, vPadding = 0) => {
+export const aboveLeftOf = (elementRect: DOMRect, chevronFace = ChevronFace.None, vPadding = 0): AboveLeftOf => {
     const menuOptions: IPosition & { chevronFace: ChevronFace } = { chevronFace };
 
     const buttonRight = elementRect.right + window.pageXOffset;

src/components/views/rooms/MessageComposer.tsx

@@ -32,6 +32,7 @@ import {
     ContextMenu,
     useContextMenu,
     MenuItem,
+    AboveLeftOf,
 } from "../../structures/ContextMenu";
 import AccessibleTooltipButton from "../elements/AccessibleTooltipButton";
 import ReplyPreview from "./ReplyPreview";
@@ -511,7 +512,7 @@ export default class MessageComposer extends React.Component<IProps, IState> {
                 null,
         ];
 
-        let menuPosition;
+        let menuPosition: AboveLeftOf | undefined;
         if (this.ref.current) {
             const contentRect = this.ref.current.getBoundingClientRect();
             menuPosition = aboveLeftOf(contentRect);