I am editing mouse settings in the registry but they seem to do nothing

Question

I have made a program to change the mouse sensivity in the same way as you can do it with the Control Panel. The changes are made in the registry, the keys at HKEY_CURRENT_USER\Control Panel\Mouse and they are in fact done (I have checked them from regedit.exe) but the mouse works as if this changes are not made. In other words, the changes do not take any effect, they only do if you use the control panel. Why do they not take effect?

Answer 1

Windows registry isn't something that is refreshed all the time. The changes you made will be applied after the current user (that's why it's HKEY_CURRENT_USER) logs in again, or as you said after using control panel, which will read the registry. I don't know, what language your program is written in, but you should check out this link: "https://msdn.microsoft.com/en-us/library/ms724947.aspx"

Answer 2

In general, tweaking registry settings directly is unsupported, especially when there's an API to tweak the setting. In this case, the API is SystemParametersInfo. In particular, you need to use the SPI_SETMOUSESPEED as the argument for the uiAction parameter.

In other words, the changes do not take any effect, they only do if you use the control panel. Why do they not take effect?

Because there's often a little more to it than setting the value in the registry. Often there is a notification that must be sent after changing the value in order to tell the all the other software on the machine to drop any cached values and replace them with the new value that's now in the registry. In many cases, the notification will be in the form of a broadcast message.

In the case of mouse driver settings, you probably need to use the SPIF_UPDATEINIFILE argument for the fWinIni parameter. You might also need to OR it with SPIF_SENDCHANGE to broadcast a WM_SETTINGCHANGE message, but I'm not sure about that.