Memory problem of the directx tool kit sample "Direct3D with XAML Marble Maze"

Apr 8, 2013 at 3:41 AM
Edited Apr 8, 2013 at 5:03 AM
A few days ago I met some memory leak problem in my d3d+xaml program.I checked my code, but still did not find out why.Then I would like to refer to the sample of "Direct3D with XAML Marble Maze",but I found it seems there is a memory leak problem also.

My steps are as follows:
(1)
Run the Direct3D with XAML Marble Maze on lumia620_nokia.The memory used is 21336kb.
(2)
Repeat the following steps like this: A B B B A B B B A A B B A A A B B................
A~ Switch between "Drawing Surface" and "Background Grid" mode;
B~ Hold the back button "<-" to switch to other program and then back to Marble Maze;
(3)
Then I found the memory used is larger and larger(100344kb,120384kb,129012kb,,,,,,,,).

I want to know what is causing a memory leak like that.
My aim is to gain experience about memory in order to analyze memory problems in my program.