SetScrollHere() tweak to make the code a little less confusing

imgui.cpp

@@ -5310,8 +5310,9 @@ void ImGui::SetScrollFromPosY(float pos_y, float center_y_ratio)
 void ImGui::SetScrollHere(float center_y_ratio)
 {
     ImGuiWindow* window = GetCurrentWindow();
-    float target_y = window->DC.CursorPosPrevLine.y + (window->DC.PrevLineHeight * center_y_ratio) + (GImGui->Style.ItemSpacing.y * (center_y_ratio - 0.5f) * 2.0f); // Precisely aim above, in the middle or below the last line.
-    SetScrollFromPosY(target_y - window->Pos.y, center_y_ratio);
+    float target_y = window->DC.CursorPosPrevLine.y - window->Pos.y; // Top of last item, in window space
+    target_y += (window->DC.PrevLineHeight * center_y_ratio) + (GImGui->Style.ItemSpacing.y * (center_y_ratio - 0.5f) * 2.0f); // Precisely aim above, in the middle or below the last line.
+    SetScrollFromPosY(target_y, center_y_ratio);
 }
 
 void ImGui::SetKeyboardFocusHere(int offset)