fix data types returned

src/Entity/Browser/Container/Tab.php

@@ -59,8 +59,8 @@ class Tab
         $this->gtk->connect(
             'switch-page',
             function(
-                ?GtkNotebook $self,
-                ?GtkWidget $child,
+                GtkNotebook $self,
+                GtkWidget $child,
                 int $page_num
             ) {
                 // Update header bar title
@@ -81,8 +81,8 @@ class Tab
         $this->gtk->connect(
             'page-added',
             function(
-                ?GtkNotebook $self,
-                ?GtkWidget $child,
+                GtkNotebook $self,
+                GtkWidget $child,
                 int $page_num
             ) {
                 $this->reorder();
@@ -92,8 +92,8 @@ class Tab
         $this->gtk->connect(
             'page-removed',
             function(
-                ?GtkNotebook $self,
-                ?GtkWidget $child,
+                GtkNotebook $self,
+                GtkWidget $child,
                 int $page_num
             ) {
                 // Free memory pool
@@ -114,8 +114,8 @@ class Tab
         $this->gtk->connect(
             'page-reordered',
             function(
-                ?GtkNotebook $self,
-                ?GtkWidget $child,
+                GtkNotebook $self,
+                GtkWidget $child,
                 int $page_num
             ) {
                 $this->reorder();
@@ -147,8 +147,8 @@ class Tab
         $label->connect(
             'button-press-event',
             function(
-                ?GtkEventBox $self,
-                ?GdkEvent $event
+                GtkEventBox $self,
+                GdkEvent $event
             ) {
                 // Close tab on double click
                 if ($event->type == Gdk::DOUBLE_BUTTON_PRESS)