Loading Bar?

For the theory part:
1. You have to know how many files you have to load
2. load file by file
3. After each file has been loaded you calculate the percentage of files loaded in comparison to maximum
4. You draw some kind of output

Another examplecode (only checking for complete files loaded):

Graphics 640, 480, 16, 2
SetBuffer BackBuffer()

total = 100

Dim files(total)

For i = 1 To total
	files(i) = CreateImage(320,320) ; Create or Load files/media
	Cls
	Text 320, 240, "Loading...", True, True
	Rect 240, 280, Float(i) / Float(total) * 160, 20, True
	Flip
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