Invite UX tweaks:

+ re-focus input field after all interactions
+ change textarea to text input
+ fix margins between things
+ improve keyboard usage with enter/space autofilling

res/css/views/dialogs/_InviteDialog.scss

@@ -27,37 +27,29 @@ limitations under the License.
         padding-left: 8px;
         overflow-x: hidden;
         overflow-y: auto;
+        display: flex;
+        flex-wrap: wrap;
 
         .mx_InviteDialog_userTile {
+            margin: 6px 6px 0 0;
             display: inline-block;
-            float: left;
-            position: relative;
-            top: 7px;
+            min-width: max-content; // prevent manipulation by flexbox
         }
 
-        // Using a textarea for this element, to circumvent autofill
-        // Mostly copied from AddressPickerDialog
-        textarea,
-        textarea:focus {
-            height: 34px;
-            line-height: $font-34px;
+        // Mostly copied from AddressPickerDialog; overrides bunch of our default text input styles
+        input, input:focus {
+            margin: 6px 0 !important;
+            height: 24px;
+            line-height: $font-24px;
             font-size: $font-14px;
             padding-left: 12px;
-            margin: 0 !important;
             border: 0 !important;
             outline: 0 !important;
             resize: none;
-            overflow: hidden;
             box-sizing: border-box;
-            word-wrap: nowrap;
-
-            // Roughly fill about 2/5ths of the available space. This is to try and 'fill' the
-            // remaining space after a bunch of pills, but is a bit hacky. Ideally we'd have
-            // support for "fill remaining width", but traditional tricks don't work with what
-            // we're pushing into this "field". Flexbox just makes things worse. The theory is
-            // that users won't need more than about 2/5ths of the input to find the person
-            // they're looking for.
-            width: 40%;
+            min-width: 40%;
+            flex: 1 !important;
+            color: $primary-fg-color !important;
         }
     }
 

src/components/views/dialogs/InviteDialog.js

@@ -663,12 +663,21 @@ export default class InviteDialog extends React.PureComponent {
     };
 
     _onKeyDown = (e) => {
-        // when the field is empty and the user hits backspace remove the right-most target
-        if (!e.target.value && !this.state.busy && this.state.targets.length > 0 && e.key === Key.BACKSPACE &&
-            !e.ctrlKey && !e.shiftKey && !e.metaKey
-        ) {
+        if (this.state.busy) return;
+        const value = e.target.value.trim();
+        const hasModifiers = e.ctrlKey || e.shiftKey || e.metaKey;
+        if (!value && this.state.targets.length > 0 && e.key === Key.BACKSPACE && !hasModifiers) {
+            // when the field is empty and the user hits backspace remove the right-most target
             e.preventDefault();
             this._removeMember(this.state.targets[this.state.targets.length - 1]);
+        } else if (value && e.key === Key.ENTER && !hasModifiers) {
+            // when the user hits enter with something in their field try to convert it
+            e.preventDefault();
+            this._convertFilter();
+        } else if (value && e.key === Key.SPACE && !hasModifiers && value.includes("@") && !value.includes(" ")) {
+            // when the user hits space and their input looks like an e-mail/MXID then try to convert it
+            e.preventDefault();
+            this._convertFilter();
         }
     };
 
@@ -811,6 +820,10 @@ export default class InviteDialog extends React.PureComponent {
             filterText = ""; // clear the filter when the user accepts a suggestion
         }
         this.setState({targets, filterText});
+
+        if (this._editorRef && this._editorRef.current) {
+            this._editorRef.current.focus();
+        }
     };
 
     _removeMember = (member: Member) => {
@@ -820,6 +833,10 @@ export default class InviteDialog extends React.PureComponent {
             targets.splice(idx, 1);
             this.setState({targets});
         }
+
+        if (this._editorRef && this._editorRef.current) {
+            this._editorRef.current.focus();
+        }
     };
 
     _onPaste = async (e) => {
@@ -829,7 +846,7 @@ export default class InviteDialog extends React.PureComponent {
             return;
         }
 
-        // Prevent the text being pasted into the textarea
+        // Prevent the text being pasted into the input
         e.preventDefault();
 
         // Process it as a list of addresses to add instead
@@ -1024,8 +1041,8 @@ export default class InviteDialog extends React.PureComponent {
             <DMUserTile member={t} onRemove={!this.state.busy && this._removeMember} key={t.userId} />
         ));
         const input = (
-            <textarea
-                rows={1}
+            <input
+                type="text"
                 onKeyDown={this._onKeyDown}
                 onChange={this._updateFilter}
                 value={this.state.filterText}
@@ -1033,6 +1050,7 @@ export default class InviteDialog extends React.PureComponent {
                 onPaste={this._onPaste}
                 autoFocus={true}
                 disabled={this.state.busy}
+                autoComplete="off"
             />
         );
         return (