Modal closes when window regains mouse focus

[mattrberry]

Version/Branch of Dear ImGui:

Version: 1.84 WIP (18302)
Branch: master

Back-end/Renderer/Compiler/OS

Back-ends: imgui_impl_sdl.cpp + imgui_impl_opengl3.cpp
Operating System: Ubuntu 20.04

My Issue/Question:

In my example below, I render the main menu bar only when the SDL window has focus. In the menu bar, I have a single menu and menu item to open a modal. This modal opens and behaves as expected until the window loses and regains focus, at which point the modal closes. 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!

Screenshots/Video

2021-07-13.22-44-48.mp4

Standalone, minimal, complete and verifiable example:

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();
}

[ocornut]

Thanks, I could easily confirm the bug by changing if (SDL_GetMouseFocus()) { to if (!ImGui::GetIO().KeyShift. In fact, it would work with any type of window:

if (!ImGui::GetIO().KeyShift)
{
    ImGui::Begin("stealing focus");
    ImGui::End();
}

It seems peculiar that we haven't stumbled on this issue before, but I guess the majority of code written wouldn't spawn new window under a modal while a modal is active.

Not strictly the same as #4308 but I guess we may look into fixing both at the same time.

[PathogenDavid]

@mattrberry If you want a temporary workaround while Omar works on a proper fix, you can add ImGuiWindowFlags_NoFocusOnAppearing to this line in imgui_widgets.cpp:

imgui/imgui_widgets.cpp

Line 6754 in 17ec4f1

ImGuiWindowFlags window_flags = ImGuiWindowFlags_NoScrollbar | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_MenuBar;

[ocornut]

I looked at it a little bit and Rokups will investigate further but I think the fix is not going to be super easy to implement, focusing is a little complex right now.

May not directly related (unsure), but I'm aiming to move the FocusWindow() call done in Begin() to the end of level in order to solve #2304, but doing so required lots of yak-shaving already and some more (I'm nearly done with making NavInitWindow usable in parallel on multiple windows which is one of the immediate blocking thing).

[mattrberry]

Thanks so much for taking a look! I'm looking forward to the solution :)

Thanks @PathogenDavid for the temporary workaround!

[ocornut]

Hello @mattrberry,

For the specific problem of modal closing we have a potential fix by @rokups coming but as i'm hoping to tag 1.84 I think that may be too risky for a merge right now, so we'll probably merge that between 1.84 and 1.85.

Generally speaking if your modal was a regular popup you would have a similar problem and the fix for modal wouldn't apply the same way. Considering how you are hiding/showing that menu-bar the proper fix may be to simply add the ImGuiWindowFlags_NoFocusOnAppearing flag to the window hosting your main menu bar, as suggested above.

The way to do that would be to copy BeginMainMenuBar() in your own code (with a different name).
That function has a little extra cruft because it tries to handle safe display area, which is almost never something you'd care for nowadays, so if you strip that safe area code off your function becomes a simple:

bool BeginMyMainMenuBar()
{
    using namespace ImGui;
    bool is_open = 
        BeginViewportSideBar("##MainMenuBar", viewport, ImGuiDir_Up, 
            GetFrameHeight(), 
            ImGuiWindowFlags_NoScrollbar | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_MenuBar | ImGuiWindowFlags_NoFocusOnAppearing);
    if (is_open)
        BeginMenuBar();
    else
        End();
    return is_open;
}

[mattrberry]

Hi Omar, that makes sense that you want to tag 1.84. That sounds good. Thank you both for the workaround for the time being! I appreciate the help with this issue :)

[ocornut]

We have pushed a bunch of commit related to solving this.
Changelog says:

- Modals, Popups, Windows: changes how appearing windows are interrupting popups and modals. (#4317) [@rokups]
  - appearing windows created from within the begin stack of a popup/modal will no longer close it.
  - appearing windows created not within the begin stack of a modal will no longer close the modal,
    and automatically appear behind it.

AFAIK it should now be solved, however it is has been a really long road full of issues, bugs and other requires changes (we had to rewrite how the dimming system worked). Not ruling out the possibility that there might be other issues.. we'll keep this open for a while.

[ocornut]

For future ref, the trail of commits leading to this:

1ab3007 Viewports: Fixed CTRL+TAB highlight outline on docked windows not always fitting in host viewport + moved EndFrameDrawDimmedBackgrounds() call + removed duplicate code in Begin() already in EndFrameDrawDimmedBackgrounds()
f087a5b Metrics: Added a node showing windows in submission order and showing the Begin() stack.
5b1a70a Fixed RenderRectFilledWithHole() (used by docking) + added dummy EndFrameDrawDimmedBackgrounds() stub in master. The round corner flag change in 033dfd9 forgot to default to _None.
8733ca4 Docking: Fixed single-frame node pos/size inconsistencies when window stop or start being submitted. Fix 718e15c while preserving its intended property. Tested by "docking_window_appearing_layout". (#2109)
657073a Nav, Docking: fix dimming crash with accessing zero-cmd ImDrawList (amend 1dc3af3, 23ef6c1)
b38af0f Popups: Fix popups being closed by newly appearing windows. (#4317) * Popups/modals now remain open when new windows are created from within popup/modal begin stack. * Modals are not closed when new window appears behind active modal. Tested by "window_popup_interruptions"
c80e8b9 Backends: OpenGL2, Marmalade: Fixed mishandling of the ImDrawCmd::IdxOffset field. (#4790)
a19815d Backends: Allegro5: Fixed mishandling of the ImDrawCmd::IdxOffset field. (#4790)
270d4d0 Nav, Docking: Fix crash on dimming docked window and DockSpaceOverViewport() with PassthruCentralNode.
b16f738 Docking: docked windows honor ImGuiCol_WindowBg. Host window in charge of rendering seams.
c122c0e Docking: Amend b16f738 fixed dimming of docked window + removed thin highlight around windows (never worked on docked window, not viewports friendly, hard to move to EndFrame) (#2700, #2539, #2522)
1dc3af3 Nav, Docking: reworked modal/ctrl+tab dimming system to be entirely processed at end of the frame, which will simplify things for an upcoming commit. (Will backport some of this back to master now.)
fc198fe Nav, Docking: Fix dimming on docked windows.
e03383d Fixes for tooltip over modals leading to incorrect modal dimming. (#4729)
0647cf4 Nav, Docking: Fix crash on dimming docked window and DockSpaceOverViewport() with PassthruCentralNode.
747f7fd Docking: prevent docking any window created above a popup/modal. (#4317)

[mattrberry]

Thank you so much for the detailed followup on this! Looking forward to trying it out :)

[mattrberry]

Looks to me like it's working as intended! Thanks again for this!