No need for all those macros - they seem to be confusing you.
On the Microsoft site you would have seen this
BOOL ShowWindow(
HWND hWnd,
int nCmdShow
);
That is the syntax for ShowWindow, now the parameters are hWnd and nCmdShow. Looking down where the parameters are you can see SW_HIDE. Sounds appropriate. So,
ShowWindow(hEditControl, SW_HIDE);
Will do it for you. When you want to show the edit control again use SW_SHOW instead of SW_HIDE.
All controls are in fact windows, btw.
If you don't have the edit control handle use
HWND GetDlgItem(
HWND hDlg,
int nIDDlgItem
);
Where hDlg is the handle to the main window or the diloag box.
nIDDlgItem is the control identifier used when you created the control.
For example - if you created the edit window with CreateWindow the 10th parameter was the indentifier, the one before hInstance.
hwnd = CreateWindowEx( "", "", "", "",
0, 0, 0, 0, hwndParent, (HMENU)IDENTIFIER, hInstance, NULL);
Or if you used a dialog then there would have been something like this
CONTROL "", ID_FILTER, "Edit", ES_AUTOHSCROLL|WS_BORDER|WS_TABSTOP, 8, 20, 100, 12
Where ID_FILTER was the indentifier.
John