Tables: Fixed top-most outer border being drawn with both TableBorderLight and TableBorderStrong in some situations, causing the earlier to be visible underneath when alpha is not 1.0f.

docs/CHANGELOG.txt

@@ -57,6 +57,8 @@ Other changes:
   Previously was inconsistent and only enabled when stepping through a non-input item.
   (#6802, #3092, #5759, #787)
 - Tables: Fixed bottom-most and right-most outer border offset by one. (#6765, #3752) [@v-ein]
+- Tables: Fixed top-most outer border being drawn with both TableBorderLight and TableBorderStrong
+  in some situations, causing the earlier to be visible underneath when alpha is not 1.0f.
 - Fonts: 'float size_pixels' passed to AddFontXXX() functions is now rounded to lowest integer.
   This is because our layout/font system currently doesn't fully support non-integer sizes. Until
   it does, this has been a common pitfall leading to more or less subtle issues. (#3164, #3309, #6800)

imgui_tables.cpp

@@ -1840,15 +1840,14 @@ void ImGui::TableEndRow(ImGuiTable* table)
             bg_col1 = table->RowBgColor[1];
 
         // Decide of top border color
-        ImU32 border_col = 0;
+        ImU32 top_border_col = 0;
         const float border_size = TABLE_BORDER_SIZE;
-        if (table->CurrentRow > 0 || table->InnerWindow == table->OuterWindow)
-            if (table->Flags & ImGuiTableFlags_BordersInnerH)
-                border_col = (table->LastRowFlags & ImGuiTableRowFlags_Headers) ? table->BorderColorStrong : table->BorderColorLight;
+        if (table->CurrentRow > 0 && (table->Flags & ImGuiTableFlags_BordersInnerH))
+            top_border_col = (table->LastRowFlags & ImGuiTableRowFlags_Headers) ? table->BorderColorStrong : table->BorderColorLight;
 
         const bool draw_cell_bg_color = table->RowCellDataCurrent >= 0;
         const bool draw_strong_bottom_border = unfreeze_rows_actual;
-        if ((bg_col0 | bg_col1 | border_col) != 0 || draw_strong_bottom_border || draw_cell_bg_color)
+        if ((bg_col0 | bg_col1 | top_border_col) != 0 || draw_strong_bottom_border || draw_cell_bg_color)
         {
             // In theory we could call SetWindowClipRectBeforeSetChannel() but since we know TableEndRow() is
             // always followed by a change of clipping rectangle we perform the smallest overwrite possible here.
@@ -1887,8 +1886,8 @@ void ImGui::TableEndRow(ImGuiTable* table)
         }
 
         // Draw top border
-        if (border_col && bg_y1 >= table->BgClipRect.Min.y && bg_y1 < table->BgClipRect.Max.y)
-            window->DrawList->AddLine(ImVec2(table->BorderX1, bg_y1), ImVec2(table->BorderX2, bg_y1), border_col, border_size);
+        if (top_border_col && bg_y1 >= table->BgClipRect.Min.y && bg_y1 < table->BgClipRect.Max.y)
+            window->DrawList->AddLine(ImVec2(table->BorderX1, bg_y1), ImVec2(table->BorderX2, bg_y1), top_border_col, border_size);
 
         // Draw bottom border at the row unfreezing mark (always strong)
         if (draw_strong_bottom_border && bg_y2 >= table->BgClipRect.Min.y && bg_y2 < table->BgClipRect.Max.y)