Method TableOpenContextMenu

core/src/imgui/imgui_tables.cpp:2984–3001

Use -1 to open menu not specific to a given column.

// Use -1 to open menu not specific to a given column.
void ImGui::TableOpenContextMenu(int column_n)
{
    ImGuiContext& g = *GImGui;
    ImGuiTable* table = g.CurrentTable;
    if (column_n == -1 && table->CurrentColumn != -1)   // When called within a column automatically use this one (for consistency)
        column_n = table->CurrentColumn;
    if (column_n == table->ColumnsCount)                // To facilitate using with TableGetHoveredColumn()
        column_n = -1;
    IM_ASSERT(column_n >= -1 && column_n < table->ColumnsCount);
    if (table->Flags & (ImGuiTableFlags_Resizable | ImGuiTableFlags_Reorderable | ImGuiTableFlags_Hideable))
    {
        table->IsContextPopupOpen = true;
        table->ContextPopupColumn = (ImGuiTableColumnIdx)column_n;
        table->InstanceInteracted = table->InstanceCurrent;
        const ImGuiID context_menu_id = ImHashStr("##ContextMenu", 0, table->ID);
        OpenPopupEx(context_menu_id, ImGuiPopupFlags_None);
    }
}

// Output context menu into current window (generally a popup)
// FIXME-TABLE: Ideally this should be writable by the user. Full programmatic access to that data?