Parallels C API Reference Guide
Sends a request to a virtual machine to adjust the screen resolution of the guest OS to specified values.
The guest OS can accept or reject the new resolution depending on compatibility factors. The function does not provide information on whether the new resolution was accepted or not. The PRL_ERR_SECCESS return code means that the function didn't fail but it doesn't mean that the screen resolution was actually changed. To verify the results of the operation, you can capture the guest OS screen before and after executing this function and compare the results. You can use this function only if the Parallels Tools package is installed in the target virtual machine and if the Dynamic Resolution feature is turned on. To determine the status of the Dynamic Resolution feature, use the PrlDevDisplay_GetDynResToolStatus function.