fix(ui-overlays): add maskcounter

Closes: INSTUI-3855

packages/ui-overlays/src/Mask/MaskCounter.ts

@@ -0,0 +1,49 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2015 - present Instructure, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+const MaskCounter = (() => {
+
+  let counter = 0
+  const getCounter = () => counter
+  const setCounter = (value: number) => {
+    counter = value
+  }
+  const incrementCounter = () => {
+    setCounter(getCounter() + 1)
+  }
+
+  const decrementCounter = () => {
+    setCounter(getCounter() - 1)
+  }
+
+  return {
+    getCounter,
+    setCounter,
+    incrementCounter,
+    decrementCounter
+  }
+})()
+
+
+export default MaskCounter

packages/ui-overlays/src/Mask/index.tsx

@@ -39,6 +39,7 @@ import generateComponentTheme from './theme'
 
 import type { MaskProps } from './props'
 import { allowedProps, propTypes } from './props'
+import MaskCounter from './MaskCounter'
 
 /**
 ---
@@ -63,6 +64,7 @@ class Mask extends Component<MaskProps> {
 
     if (this.props.fullscreen) {
       noScroll.on()
+      MaskCounter.incrementCounter()
     }
   }
 
@@ -72,7 +74,10 @@ class Mask extends Component<MaskProps> {
 
   componentWillUnmount() {
     if (this.props.fullscreen) {
-      noScroll.off()
+      MaskCounter.decrementCounter()
+      if (MaskCounter.getCounter() <= 0) {
+        noScroll.off()
+      }
     }
   }