Widgets are not displayed correctly in scroll. Why?

Question

linux

recorded a video. click

on the video, you can see that when you add elements that go beyond the widget area, the widget is not completely drawn on top. And when you reach the edges of the scroll, the effect that you don't want appears, which spoils the view. Here is the code. Tell me how to do it.

#include <gtk/gtk.h>
#include <time.h>
#include <string.h>

GtkWidget *menu, *item;
GtkWidget *window;
GtkApplication *app;
GtkWidget *frame_chat_view;
GtkWidget *text_box;
GtkWidget *entry_input_text;
GtkWidget *scroll;

int scroll_event = 0;

static gboolean window_delete ( GtkWidget *widget, GdkEvent *event, gpointer user_data ) {
  g_application_quit ( ( GApplication * ) app );
  exit ( EXIT_SUCCESS );
  return FALSE;
}

static gboolean text_view_draw_cb ( GtkWidget *widget, cairo_t *cr, gpointer data ) {
  gtk_widget_queue_resize ( widget );
  GtkAdjustment *vadj = gtk_scrolled_window_get_vadjustment ( ( GtkScrolledWindow * ) scroll );
  if ( scroll_event == 0 ) {
    gtk_adjustment_set_value ( vadj, gtk_adjustment_get_upper ( vadj ) );
  } else {
    gtk_adjustment_set_value ( vadj, gtk_adjustment_get_value ( vadj ) );
  }
  return FALSE;
}


static gboolean scroll_scroll_child_cb ( GtkWidget *widget, GdkEvent *event, gpointer data ) {
  GtkAdjustment *vadj = gtk_scrolled_window_get_vadjustment ( ( GtkScrolledWindow * ) scroll );
  gtk_adjustment_set_value ( vadj, gtk_adjustment_get_value ( vadj ) );
  scroll_event = 1;

  return FALSE; 
}

const char *style = "* { background-color: #3c3c3c; } entry { color: #ffffff; } frame#frame_text * { background-color: #1c1c1c; border-radius: 6px; } textview text { color: #ffffff; } textview#text_view_w * { border-radius: 0px; }";
int index_list = 0;

static gboolean entry_input_text_cb ( GtkWidget *widget, GdkEvent *event, gpointer data ) {
  GdkEventKey *key = ( GdkEventKey * ) event;
  if ( key->keyval == GDK_KEY_Return ) {
    scroll_event = 0;
    const char *t = gtk_entry_get_text ( ( GtkEntry * ) entry_input_text );
    if ( strlen ( t ) == 0 ) return FALSE;

    GtkTextBuffer *buf = gtk_text_buffer_new ( NULL );
    gtk_text_buffer_set_text ( buf, t, -1 );

    GtkWidget *frame = g_object_new ( GTK_TYPE_FRAME, "shadow-type", GTK_SHADOW_NONE, "name", "frame_text", NULL );

    GtkWidget *text_view = gtk_text_view_new ( );
    gtk_text_view_set_editable ( ( GtkTextView * ) text_view, FALSE );
    gtk_text_view_set_wrap_mode ( ( GtkTextView * ) text_view, GTK_WRAP_WORD_CHAR );
    gtk_text_view_set_buffer ( ( GtkTextView * ) text_view, buf );

    g_signal_connect ( text_view, "draw", G_CALLBACK ( text_view_draw_cb ), NULL );

    gtk_widget_set_name ( text_view, "text_view_w" );
    gtk_widget_set_margin_start ( frame, 10 );
    gtk_widget_set_margin_end ( frame, 10 );
    gtk_widget_set_margin_top ( frame, 10 );
    gtk_widget_set_margin_bottom ( frame, 0 );

    gtk_widget_set_margin_top ( text_view, 10 );
    gtk_widget_set_margin_end ( text_view, 10 );
    gtk_widget_set_margin_bottom ( text_view, 10 );
    gtk_widget_set_margin_start ( text_view, 10 );

    gtk_container_add ( ( GtkContainer * ) frame, text_view );

    gtk_box_pack_start ( ( GtkBox * ) text_box, frame, FALSE, FALSE, 0 );

    gtk_widget_show_all ( text_box );

    gtk_entry_set_text ( ( GtkEntry * ) entry_input_text, "" );

  }

  return FALSE;
}

static void g_startup ( GtkApplication *app, gpointer data ) {
  GMainLoop *loop = g_main_loop_new ( NULL, FALSE );

  window = gtk_application_window_new ( app );

  gtk_window_set_default_size ( ( GtkWindow * ) window, 1024, 600 );

  GdkDisplay *display = gdk_display_get_default ();
    	GdkScreen *screen = gdk_display_get_default_screen (display);
  GtkCssProvider *pr = gtk_css_provider_new ( );

  GError *error;
    	gtk_style_context_add_provider_for_screen (screen, GTK_STYLE_PROVIDER (pr), GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
  gtk_css_provider_load_from_data ( ( GtkCssProvider * ) pr, style, strlen ( style ), NULL );

  GtkStyleContext *ctx = gtk_style_context_new ( );
  gtk_style_context_add_provider ( ( GtkStyleContext * ) ctx, ( GtkStyleProvider * ) pr, GTK_STYLE_PROVIDER_PRIORITY_USER );

  frame_chat_view = g_object_new ( GTK_TYPE_FRAME, "shadow-type", GTK_SHADOW_NONE, NULL );

  g_signal_connect ( window, "delete-event", G_CALLBACK ( window_delete ), NULL );

  GtkWidget *main_box = gtk_box_new ( GTK_ORIENTATION_VERTICAL, 0 );
  GtkWidget *input_box = gtk_box_new ( GTK_ORIENTATION_HORIZONTAL, 0 );
  text_box = gtk_box_new ( GTK_ORIENTATION_VERTICAL, 0 );
  gtk_widget_set_name ( text_box, "text_box" );

  entry_input_text = gtk_entry_new ( );

  scroll = g_object_new ( GTK_TYPE_SCROLLED_WINDOW, "shadow-type", GTK_SHADOW_NONE, "hadjustment", NULL, "vadjustment", NULL, NULL );
  gtk_scrolled_window_set_policy ( ( GtkScrolledWindow * ) scroll, GTK_POLICY_NEVER, GTK_POLICY_AUTOMATIC );
  g_signal_connect ( scroll, "scroll-event", G_CALLBACK ( scroll_scroll_child_cb ), NULL );
  gtk_container_add ( ( GtkContainer * ) frame_chat_view, text_box );
  gtk_container_add ( ( GtkContainer * ) scroll, frame_chat_view );

  gtk_box_pack_start ( ( GtkBox * )  main_box, scroll, TRUE, TRUE, 0 );
  gtk_box_pack_start ( ( GtkBox * )  main_box, input_box, FALSE, FALSE, 0 );

  gtk_box_pack_end ( ( GtkBox * ) input_box, entry_input_text, TRUE, TRUE, 0 );

  g_signal_connect ( entry_input_text, "key-press-event", G_CALLBACK ( entry_input_text_cb ), NULL );


  gtk_container_add ( ( GtkContainer * ) window, main_box );
  gtk_widget_show_all ( window );
  g_main_loop_run ( loop );
}

int main ( int argc, char **argv ) {
  app = gtk_application_new ( "org.xverizex.lanxchat", G_APPLICATION_FLAGS_NONE );
  g_application_register ( ( GApplication * ) app, NULL, NULL );
  g_signal_connect ( app, "activate", G_CALLBACK ( g_startup ), NULL );
  int ret = g_application_run ( ( GApplication * ) app, argc, argv );
  g_object_unref ( app );
  return ret;

}