Remove border roundness inside panels of `AcceptDialog` windows

scene/theme/default_theme.cpp

@@ -639,7 +639,7 @@ void fill_default_theme(Ref<Theme> &theme, const Ref<Font> &default_font, const
 	// Dialogs
 
 	// AcceptDialog is currently the base dialog, so this defines styles for all extending nodes.
-	theme->set_stylebox("panel", "AcceptDialog", make_flat_stylebox(style_popup_color, Math::round(8 * scale), Math::round(8 * scale), Math::round(8 * scale), Math::round(8 * scale)));
+	theme->set_stylebox("panel", "AcceptDialog", make_flat_stylebox(style_popup_color, Math::round(8 * scale), Math::round(8 * scale), Math::round(8 * scale), Math::round(8 * scale), 0));
 	theme->set_constant("buttons_separation", "AcceptDialog", Math::round(10 * scale));
 
 	// File Dialog