Different expanding performance for Dropdown in different order

[bleakglory]

When placing multiple Dropdown components inside a Container::Vertical, their interactive behavior becomes inconsistent depending on the order in which they are clicked.

When clicking from top to bottom (i.e., first the topmost, then the one below), the previously opened dropdown correctly closes before the next one gains focus.

However, when clicking in reverse order (from bottom to top), the previously opened dropdown does not close. This results in two (or more) dropdown menus staying open simultaneously, overlapping and creating a confusing UI state.

It seems like it is related to the OnEvent handling order and i am not sure whether it can be identified as a problem.

[ArthurSonzogni]

Hi @bleakglory , could you please post a minimal reproducer of the issue?

[c-fido]

I can reproduce it here.

#include <string>
#include <vector>
#include "ftxui/component/component.hpp"
#include "ftxui/component/screen_interactive.hpp"
int main() {
  using namespace ftxui;
  std::vector<std::string> entries = {"alpha", "bravo", "charlie", "delta"};
  int top = 0, bottom = 0;
  auto screen = ScreenInteractive::FitComponent();
  screen.Loop(Container::Vertical({
      Dropdown(&entries, &top),
      Dropdown(&entries, &bottom),
  }));
}

If you click the bottom Dropdown then the top one, both stay open. Then if you click on the bottom Dropdown, the top one closes and the bottom stays open.

While open, Dropdown treats any left click as close and swallows it, so the one below never sees the event. The open list also overlaps the control underneath.

A possible fix in OnRender: if (open_() && !Focused()) *open_ = false;