Pierre-Antoine,
Thank you for your post.
This two property get the actual height & width in pixels, of the map control.
When you set your map’s height with percentage values (for example, 100%), you might want to know the actual pixel height of your map at a given time. This property returns the map’s pixel height as determined by the browser.
But please notice when the map height is a percent value, the HeightInPixels is double. NaN only until a postback generates. When the page postbacks, the actual height of the map will be synchronized to this property.
Regards,
Gary