Separator: Fixed zero-height bounding box resulting in clipping when at top of clipping rectangle (#860)

imgui.cpp

@@ -9092,8 +9092,8 @@ void ImGui::Separator()
     if (!window->DC.GroupStack.empty())
         x1 += window->DC.IndentX;
 
-    const ImRect bb(ImVec2(x1, window->DC.CursorPos.y), ImVec2(x2, window->DC.CursorPos.y));
-    ItemSize(ImVec2(0.0f, 0.0f)); // NB: we don't provide our width so that it doesn't get feed back into AutoFit   // FIXME: Height should be 1.0f not 0.0f ?
+    const ImRect bb(ImVec2(x1, window->DC.CursorPos.y), ImVec2(x2, window->DC.CursorPos.y+1.0f));
+    ItemSize(ImVec2(0.0f, 0.0f)); // NB: we don't provide our width so that it doesn't get feed back into AutoFit, we don't provide height to not alter layout.
     if (!ItemAdd(bb, NULL))
     {
         if (window->DC.ColumnsCount > 1)
@@ -9101,7 +9101,7 @@ void ImGui::Separator()
         return;
     }
 
-    window->DrawList->AddLine(bb.Min, bb.Max, GetColorU32(ImGuiCol_Border));
+    window->DrawList->AddLine(bb.Min, ImVec2(bb.Max.x,bb.Min.y), GetColorU32(ImGuiCol_Border));
 
     ImGuiContext& g = *GImGui;
     if (g.LogEnabled)