Demo: comments (#414)

imgui.cpp

@@ -410,6 +410,7 @@
  - window: get size/pos helpers given names (see discussion in #249)
  - window: a collapsed window can be stuck behind the main menu bar?
  - window: detect extra End() call that pop the "Debug" window out and assert at call site instead of later.
+ - window/tooltip: allow to set the width of a tooltip to allow TextWrapped() etc. while keeping the height automatic.
  - draw-list: maintaining bounding box per command would allow to merge draw command when clipping isn't relied on (typical non-scrolling window or non-overflowing column would merge with previous command).
 !- scrolling: allow immediately effective change of scroll if we haven't appended items yet
  - splitter: formalize the splitter idiom into an official api (we want to handle n-way split)

imgui_demo.cpp

@@ -2180,6 +2180,8 @@ static void ShowExampleAppPropertyEditor(bool* opened)
         return;
     }
 
+    ShowHelpMarker("This example shows how you may implement a property editor using two columns.\nAll objects/fields data are dummies here.\nRemember that in many simple cases, you can use ImGui::SameLine(xxx) to position\nyour cursor horizontally instead of using the Columns() API.");
+
     ImGui::PushStyleVar(ImGuiStyleVar_FramePadding, ImVec2(2,2));
     ImGui::Columns(2);
     ImGui::Separator();