Improve dropdown menu keyboard navigation (#11491)

* Allow selecting menu items with the space bar in status dropdown menus

* Fix modals opened by keyboard navigation being immediately closed

* Fix menu items triggering modal actions

* Add Tab trapping inside dropdown menu

* Give focus back to last focused element when status dropdown menu closes

1 files changed, 26 insertions, 18 deletions

diff --git a/app/javascript/mastodon/components/dropdown_menu.js b/app/javascript/mastodon/components/dropdown_menu.js
index e122515c4..9937d0f88 100644
--- a/app/javascript/mastodon/components/dropdown_menu.js
+++ b/app/javascript/mastodon/components/dropdown_menu.js
@@ -45,7 +45,10 @@ class DropdownMenu extends React.PureComponent {
     document.addEventListener('click', this.handleDocumentClick, false);
     document.addEventListener('keydown', this.handleKeyDown, false);
     document.addEventListener('touchend', this.handleDocumentClick, listenerOptions);
-    if (this.focusedItem && this.props.openedViaKeyboard) this.focusedItem.focus();
+    this.activeElement = document.activeElement;
+    if (this.focusedItem && this.props.openedViaKeyboard) {
+      this.focusedItem.focus();
+    }
     this.setState({ mounted: true });
   }
 
@@ -53,6 +56,9 @@ class DropdownMenu extends React.PureComponent {
     document.removeEventListener('click', this.handleDocumentClick, false);
     document.removeEventListener('keydown', this.handleKeyDown, false);
     document.removeEventListener('touchend', this.handleDocumentClick, listenerOptions);
+    if (this.activeElement) {
+      this.activeElement.focus();
+    }
   }
 
   setRef = c => {
@@ -81,6 +87,18 @@ class DropdownMenu extends React.PureComponent {
         element.focus();
       }
       break;
+    case 'Tab':
+      if (e.shiftKey) {
+        element = items[index-1] || items[items.length-1];
+      } else {
+        element = items[index+1] || items[0];
+      }
+      if (element) {
+        element.focus();
+        e.preventDefault();
+        e.stopPropagation();
+      }
+      break;
     case 'Home':
       element = items[0];
       if (element) {
@@ -93,11 +111,14 @@ class DropdownMenu extends React.PureComponent {
         element.focus();
       }
       break;
+    case 'Escape':
+      this.props.onClose();
+      break;
     }
   }
 
-  handleItemKeyDown = e => {
-    if (e.key === 'Enter') {
+  handleItemKeyUp = e => {
+    if (e.key === 'Enter' || e.key === ' ') {
       this.handleClick(e);
     }
   }
@@ -126,7 +147,7 @@ class DropdownMenu extends React.PureComponent {
 
     return (
       <li className='dropdown-menu__item' key={`${text}-${i}`}>
-        <a href={href} target={target} data-method={method} rel='noopener' role='button' tabIndex='0' ref={i === 0 ? this.setFocusRef : null} onClick={this.handleClick} onKeyDown={this.handleItemKeyDown} data-index={i}>
+        <a href={href} target={target} data-method={method} rel='noopener' role='button' tabIndex='0' ref={i === 0 ? this.setFocusRef : null} onClick={this.handleClick} onKeyUp={this.handleItemKeyUp} data-index={i}>
           {text}
         </a>
       </li>
@@ -202,19 +223,6 @@ export default class Dropdown extends React.PureComponent {
     this.props.onClose(this.state.id);
   }
 
-  handleKeyDown = e => {
-    switch(e.key) {
-    case ' ':
-    case 'Enter':
-      this.handleClick(e);
-      e.preventDefault();
-      break;
-    case 'Escape':
-      this.handleClose();
-      break;
-    }
-  }
-
   handleItemClick = e => {
     const i = Number(e.currentTarget.getAttribute('data-index'));
     const { action, to } = this.props.items[i];
@@ -249,7 +257,7 @@ export default class Dropdown extends React.PureComponent {
     const open = this.state.id === openDropdownId;
 
     return (
-      <div onKeyDown={this.handleKeyDown}>
+      <div>
         <IconButton
           icon={icon}
           title={title}