Add minimize button to HostSignupDialog.tsx

res/css/views/dialogs/_HostSignupDialog.scss

@@ -85,6 +85,20 @@ limitations under the License.
     right: 10px;
 }
 
+.mx_HostSignup_minimize_button {
+    mask: url('$(res)/img/feather-customised/widget/minimize.svg');
+    mask-repeat: no-repeat;
+    mask-position: center;
+    mask-size: cover;
+    width: 14px;
+    height: 14px;
+    background-color: $dialog-close-fg-color;
+    cursor: pointer;
+    position: absolute;
+    top: 10px;
+    right: 10px;
+}
+
 .mx_HostSignup_persisted {
     width: 580px;
     height: 600px;

src/components/views/dialogs/HostSignupDialog.tsx

@@ -212,6 +212,10 @@ export default class HostSignupDialog extends React.PureComponent<IProps, IState
                             }
                             {!this.state.minimized &&
                                 <div className="mx_Dialog_header mx_Dialog_headerWithCancel">
+                                    <AccessibleButton
+                                        onClick={this.minimizeDialog} className="mx_HostSignup_minimize_button"
+                                        aria-label={_t("Minimize dialog")}
+                                    />
                                     <AccessibleButton
                                         onClick={this.onCloseClick} className="mx_Dialog_cancelButton"
                                         aria-label={_t("Close dialog")}