Sets the image displayed
on the button.
property ImageNormal: TPNGObject;
Description
Sets the main image displayed on the button. If the respective properties
are set, this image may be replaced by ImageDown
when the button is being pressed or ImageOver
when the cursor is over the button, otherwise this is used for all
states. When the Enabled property is false,
the components creates an transparent version of this image to make it
look like disabled.