last file opened not as "top window" on IDE 1.6.12

If the "Open Recent" menu has 10 recent files then opening another file does not put the new file as top window.
When the last to new file is full size window , the new file is completely invisible. When the last to new file is partial window , then new file will cascade under it and will be partially visible.
Could it also be that there are 10 windows active in IDE?
There is no "cascade windows" to verify that.
Jim