mdi parent and non mdi child form prob

[brenn13]

i have a mdi parent and a lot of mdi child and 1 non mdi child form.
when i run the project, the mdiparent loads the non mdi child form, which contains a tree view. under that non mdi child form is a splitter. 
when i click an item on the treeview, a mdi child loads correspond to the tree view node clicked. here is the prob, when i choose another window, for example, my documents window while the project is running, the mdi parent as well as the mdi childs went back of the my documents, but the non mdi child form remains on top of the my documents. same as when i alt+tab to select other window. i want that non mdi child form to get also at the back of any window when the mdiparent deactivate or lost its focus. can somebody help me? 
thanx in advance.

[Masudly]

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