Display of Graphics in C

Introduction:

I’ve a program which has 3 modules. Module 1 is a Labview based exe file (window) which reads and displays data from NI USB card Module 2 is a C language program based exe file (window) where functions from graphics.h are used to create graphical window which contains textboxes and progress bars to display the text read from COM port. Module 3 is also C language program based exe file (window) where functions from graphics.h are used to create graphical window which contains textboxes and progress bars to display the text read from COM port. So when I run my program, these 3 modules are initiated. I need to switch over these 3 windows(modules) to view my data which is read from 3 different ports.

My Problem:

When switching from one window to another window, either module2(window2) or module3(window3) is being displayed as blank until I close my program. Further I would not be able to view my module2/module3 data as only those modules go blank. I personally feel the graphics are not being loaded properly, when two different c graphic based windows are being executed at the same time.