I don''t know much about borland builder, but this is an idea that might work; maybe you should use a set of controls instead of a new window. Just draw some new controls (with controls I mean the sort of controls like in visual basic) on top of the editor textbox, so you don''t have to mess with the focus-stuff.

Have a function that brings up a dialog box the contains a listbox containg the auto complete items. Have the function return what is selected from the list box. If nothing is selected, return an empty string.

You can still use the dialog box. You need to code it so that when you hit the spacebar or the enter key, it returns the selected item. Maybe code it so that the escape key will return an emtpy string.

also, the window should be created program load and then hidden. you would fill the list box up with some data (its not a real listbox, but a specilized one) and show it in the proper place. this occers whenever you want (such as : is used and the text before matches something it can autocomplete). you would not switch focus to the listbox, but instead you would continue watching the key presses and as they are pressed update where in the list box you should be (ie the first match based on the partial match). pressing space or enter accepts the partial match, while up and down will move the hilite. ALL key presses are filtered from the edit box where the typeing occers. also you should use a child window as mentioned, but an always on top window works as well (just make sure its hidden and not being created when needed). also if there is no match, DONT default to something in the box, instead just allow the person to type as normal. escape should hide the box for the duration of typing on that word.