Method BeginViewportSideBar

tutorials/common/imgui/imgui_widgets.cpp:6873–6906

Important: calling order matters! FIXME: Somehow overlapping with docking tech. FIXME: The "rect-cut" aspect of this could be formalized into a lower-level helper (rect-cut: https://halt.software/dead-simple-layouts)

// FIXME: Somehow overlapping with docking tech.
// FIXME: The "rect-cut" aspect of this could be formalized into a lower-level helper (rect-cut: https://halt.software/dead-simple-layouts)
bool ImGui::BeginViewportSideBar(const char* name, ImGuiViewport* viewport_p, ImGuiDir dir, float axis_size, ImGuiWindowFlags window_flags)
{
    IM_ASSERT(dir != ImGuiDir_None);

    ImGuiWindow* bar_window = FindWindowByName(name);
    if (bar_window == NULL || bar_window->BeginCount == 0)
    {
        // Calculate and set window size/position
        ImGuiViewportP* viewport = (ImGuiViewportP*)(void*)(viewport_p ? viewport_p : GetMainViewport());
        ImRect avail_rect = viewport->GetBuildWorkRect();
        ImGuiAxis axis = (dir == ImGuiDir_Up || dir == ImGuiDir_Down) ? ImGuiAxis_Y : ImGuiAxis_X;
        ImVec2 pos = avail_rect.Min;
        if (dir == ImGuiDir_Right || dir == ImGuiDir_Down)
            pos[axis] = avail_rect.Max[axis] - axis_size;
        ImVec2 size = avail_rect.GetSize();
        size[axis] = axis_size;
        SetNextWindowPos(pos);
        SetNextWindowSize(size);

        // Report our size into work area (for next frame) using actual window size
        if (dir == ImGuiDir_Up || dir == ImGuiDir_Left)
            viewport->BuildWorkOffsetMin[axis] += axis_size;
        else if (dir == ImGuiDir_Down || dir == ImGuiDir_Right)
            viewport->BuildWorkOffsetMax[axis] -= axis_size;
    }

    window_flags |= ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoMove;
    PushStyleVar(ImGuiStyleVar_WindowRounding, 0.0f);
    PushStyleVar(ImGuiStyleVar_WindowMinSize, ImVec2(0, 0)); // Lift normal size constraint
    bool is_open = Begin(name, NULL, window_flags);
    PopStyleVar(2);

    return is_open;
}

bool ImGui::BeginMainMenuBar()
{