implement form with keep_cloned_controls

Author: gammasoft71

src/xtd.forms/include/xtd/forms/application.hpp

@@ -509,6 +509,7 @@ namespace xtd {
       /// @}
 
     private:
+      friend class control;
       friend class form;
       friend class input_dialog;
       friend class message_box;
@@ -538,6 +539,7 @@ namespace xtd {
       static bool system_font_size_;
       static bool use_wait_cursor_;
       static bool visual_styles_;
+      static xtd::collections::generic::list<xtd::sptr<xtd::forms::control>> top_level_forms_;
     };
   }
 }

src/xtd.forms/src/xtd/forms/application.cpp

@@ -99,6 +99,7 @@ bool application::system_controls_ = false;
 bool application::system_font_size_ = false;
 bool application::use_wait_cursor_ = false;
 bool application::visual_styles_ = false;
+xtd::collections::generic::list<xtd::sptr<xtd::forms::control>> application::top_level_forms_;
 
 event<application, event_handler> application::application_exit;
 event<application, event_handler> application::enter_thread_modal;
@@ -238,10 +239,16 @@ bool application::message_loop() noexcept {
 
 const form_collection application::open_forms() noexcept {
   auto forms = form_collection {};
+  if (keep_cloned_controls()) {
+    for (auto control : top_level_forms_)
+      forms.push_back(dynamic_cast<form&>(*control));
+    return forms;
+  }
+  
   for (auto control : control::top_level_controls_)
     forms.push_back(dynamic_cast<form&>(control.get()));
   return forms;
-  
+
   /*
   auto forms = form_collection {};
   for (intptr handle : native::application::open_forms()) {
@@ -438,6 +445,7 @@ void application::run(xtd::forms::application_context& context) {
   application::message_loop_ = false;
   internal_context_.main_form(nullptr);
   native::application::cleanup();
+  top_level_forms_.clear();
 }
 
 void application::run(const form& form) {

src/xtd.forms/src/xtd/forms/control.cpp

@@ -1206,8 +1206,10 @@ void control::on_control_appearance_changed(const event_args& e) {
 }
 
 void control::on_create_control() {
-  if (!parent().has_value())
-    top_level_controls_.add(*this);
+  if (!parent().has_value()) {
+    if (!application::keep_cloned_controls()) top_level_controls_.add(*this);
+    else top_level_controls_.add(*application::top_level_forms_[~1_z]);
+  }
   for (auto control : data_->controls) {
     control.get().data_->parent = handle();
     control.get().create_control();

src/xtd.forms/src/xtd/forms/form.cpp

@@ -63,6 +63,7 @@ form::form() : data_(xtd::new_sptr<data>()) {
   fore_color(application::style_sheet().is_system_style_sheet() ? system_colors::control_text() : default_fore_color());
   font(default_font());
   create_control();
+  application::top_level_forms_.add(as<control>(as<iclonable>(*this).clone()));
 }
 
 std::optional<form::ibutton_control_ref> form::accept_button() const noexcept {