Generalized d11d211e so regular popups (without the AlwaysAutoResize flag) also have a smaller minimum size, but reduced it to an arbitrary 4.0f instead of 1.0f to ease debugging of faulty situations. (#1909)

CHANGELOG.txt

@@ -42,7 +42,7 @@ Other Changes:
 
  - ArrowButton: Fixed to honor PushButtonRepeat() setting (and internals' ImGuiItemFlags_ButtonRepeat).
  - ArrowButton: Setup current line text baseline so that ArrowButton() + SameLine() + Text() are aligned properly.
- - Window: Allow menu windows from ignoring the style.WindowMinSize values so short menus are not padded. (#1909)
+ - Window: Allow menu and popups windows from ignoring the style.WindowMinSize values so short menus/popups are not padded. (#1909)
  - Window: Added global io.OptResizeWindowsFromEdges option to enable resizing windows from their edges and from the lower-left corner. (#1495)
  - Drag and Drop: Fixed an incorrect assert when dropping a source that is submitted after the target (bug introduced with 1.62 changes 
    related to the addition of IsItemDeactivated()). (#1875, #143)

imgui.cpp

@@ -5831,11 +5831,11 @@ static ImVec2 CalcSizeAutoFit(ImGuiWindow* window, const ImVec2& size_contents)
     else
     {
         // When the window cannot fit all contents (either because of constraints, either because screen is too small): we are growing the size on the other axis to compensate for expected scrollbar. FIXME: Might turn bigger than DisplaySize-WindowPadding.
-        const bool is_popup = (window->Flags & ImGuiWindowFlags_Popup) != 0 && (window->Flags & ImGuiWindowFlags_AlwaysAutoResize) != 0;
+        const bool is_popup = (window->Flags & ImGuiWindowFlags_Popup) != 0;
         const bool is_menu = (window->Flags & ImGuiWindowFlags_ChildMenu) != 0;
-        ImVec2 size_min(1.0f, 1.0f);
-        if (!is_popup && !is_menu)
-            size_min = style.WindowMinSize;
+        ImVec2 size_min = style.WindowMinSize;
+        if (is_popup || is_menu) // Popups and menus bypass style.WindowMinSize by default, but we give then a non-zero minimum size to facilitate understanding problematic cases (e.g. empty popups)
+            size_min = ImMin(size_min, ImVec2(4.0f, 4.0f));
         ImVec2 size_auto_fit = ImClamp(size_contents, size_min, ImMax(size_min, g.IO.DisplaySize - style.DisplaySafeAreaPadding * 2.0f));
         ImVec2 size_auto_fit_after_constraint = CalcSizeAfterConstraint(window, size_auto_fit);
         if (size_auto_fit_after_constraint.x < size_contents.x && !(window->Flags & ImGuiWindowFlags_NoScrollbar) && (window->Flags & ImGuiWindowFlags_HorizontalScrollbar))