check if a file exists [better way]

[x64Core]

if I don't want to use global variables how can I pass information to timer procedure, for example I want to use a string from

one way is to associate the data with the window (-handle)

• use WNDCLASSEX.cbWndExtra + Get/SetWindwoLong
• use Get/SetWindowLong with GWL_USERDATA
• use properties (Set/GetProp)

GWL_USERDATA looks like very interesting, thank you qWord