Tables: Fixed TableHeader() not declaring its height properly. Do NOT declare width.

imgui_tables.cpp

@@ -2133,6 +2133,7 @@ void    ImGui::TableHeader(const char* label)
     const bool selected = (table->IsContextPopupOpen && table->ContextPopupColumn == column_n && table->InstanceInteracted == table->InstanceCurrent);
     ImGuiID id = window->GetID(label);
     ImRect bb(cell_r.Min.x, cell_r.Min.y, cell_r.Max.x, ImMax(cell_r.Max.y, cell_r.Min.y + label_height + g.Style.CellPadding.y * 2.0f));
+    ItemSize(ImVec2(0.0f, label_height)); // Don't declare unclipped width, it'll be fed ContentMaxPosHeadersIdeal
     if (!ItemAdd(bb, id))
         return;