Pin applications to multiple desktops in Windows 10

The feature has now been released as one of several "Virtual Desktop Improvements" in the Windows 10 Anniversary Update (Build 14316):

You can now pin a window so it’s available on every desktop. To do this, launch Task View then right-click on the window you want to pin and choose “Show this window on all desktops”. Try pinning Skype or Groove Music so they’re always at your fingertips. And if you have a multi-mon setup, you might enjoy the ability to have your email app on the second monitor no matter which desktop you switch to.

Yep. [almost :)] Every window with WS_EX_TOOLWINDOW attribute is visible on all desktops.

Autohotkey is a great help in this. Example script - MyLoop.ahk:

WS_EX_TOOLWINDOW := 0x00000080
Loop
{
   WinSet, ExStyle, +%WS_EX_TOOLWINDOW%, ahk_class Chrome_WidgetWin_1
   Sleep,100
}

Put this in windows startup and Google Chrome window will "stick" to all virtual desktops.

Or assign this as a hotkey: Example script - MyHotkeys.ahk:

WS_EX_TOOLWINDOW := 0x00000080
+MButton::WinSet, ExStyle, ^%WS_EX_TOOLWINDOW%, A
^MButton::WinSet, AlwaysOnTop, toggle, A

Put this in windows startup and you can TOGGLE "sticky" state for any window by pressing Shift+middle button click on it.

Addition key - Ctrl+middle button click will toggle "topmost" state. Very useful.

PS: modern applications (e.g. windows 10 Calculator) somehow ignore this. Don't know why. But for windows explorer window and most of 'old applications' - it's work all right