2003-10-06  Michael Natterer  <mitch@gimp.org>

	* app/core/gimpchannel.c (gimp_channel_new_from_alpha): create
	a channel which the size of the layer, not of the image...

	* app/core/gimpchannel-select.c (gimp_channel_select_alpha):
	...and take the layer's offsets into account.

	* app/core/gimpscanconvert.[ch] (gimp_scan_convert_render): added
	off_x and off_y parameters and don't use the passed TileManager's
	offsets.

	* app/core/gimpchannel-select.c
	* app/core/gimpdrawable-stroke.c
	* app/tools/gimpiscissorstool.c: changed accordingly.