(New template) Modal closes when window regains mouse focus

[PathogenDavid]

Version

1.84 WIP (18302)

Branch

master

Platform Backend

imgui_impl_sdl

Renderer Backend

imgui_impl_opengl3

Compiler

No response

Operating System

Ubuntu 20.04

Steps to Reproduce

1. Add the code below to example_sdl_opengl3 and launch the example
2. Select File -> Open Modal in the menu bar
3. Click off the main viewport window (the menu bar will disappear)
4. Click back on the main viewport window

bool open_modal = false;
if (SDL_GetMouseFocus()) {
    if (ImGui::BeginMainMenuBar()) {
        if (ImGui::BeginMenu("File")) {
            open_modal = ImGui::MenuItem("Open Modal");
            ImGui::EndMenu();
        }
        ImGui::EndMainMenuBar();
    }
}
if (open_modal) {
    ImGui::OpenPopup("Modal");
}
ImVec2 center = ImGui::GetMainViewport()->GetCenter();
ImGui::SetNextWindowPos(center, ImGuiCond_Appearing, ImVec2(0.5f, 0.5f));
if (ImGui::BeginPopupModal("Modal", NULL, ImGuiWindowFlags_AlwaysAutoResize)) {
    if (ImGui::Button("Close")) {
        ImGui::CloseCurrentPopup();
    }
    ImGui::EndPopup();
}

Expected Behavior

The menu bar reappears and the modal stays open.

Actual Behavior

The menu bar reappears, but the modal closes unexpectedly.

2021-07-13.22-44-48.mp4

Other Details

I want to render the main menu bar only when the SDL window has focus. Ideally, the modal would remain open until I call ImGui::CloseCurrentPopup(). I'm wondering if I'm misusing modals or if this is possible a bug. Is there a preferred way to implement this behavior?

Apologies if this is a redundant question. I see #331, but my question is more of a tangent from the discussion in that issue.

Thank you for taking a look!

[PathogenDavid]

👆 Note that I did not actually add that label, it was added automagically since I was using the bug report template