Hi. I've been attempting to allow the drawing of a line, using the mouse, in the same window that the quinn curtis dll draws the graph, but i've had no success (i.e. the line does not show up). I tried to do something similar using the quinn curtis functions, but it would mean creating a new object (WGPolyline) on the fly, but this new object would need to be created after the graph has been created (i get an "serious error" message when i do this). Is it even possible to use the device context (the same window/device context that the quinn curtis dll is using) to make window GDI calls to draw on the graph with the mouse?
Arbitrarily adding a chart object (WGPolyline in your example) to a graph, after the graph has been defined in the graph building routine, will cause a runtime error with our software. You can however add chart objects after a graph has been created if you place them between WGPreAddGraphObject and WGPostAddGraphObject calls. See the manual for details regarding these two functions.