I want to start keepassX in floating mode in i3wm. my .config/i3/config contains the line  for_window [class=keepassx] floating enableand the xprop xprop _NET_WM_USER_TIME(CARDINAL) = 7578932WM_STATE(WM_STATE):        window state: Normal        icon window: 0x0_NET_WM_SYNC_REQUEST_COUNTER(CARDINAL) = 29360143_NET_WM_ICON(CARDINAL) =    Icon (64 x 64):XdndAware(ATOM) = BITMAP_MOTIF_DRAG_RECEIVER_INFO(_MOTIF_DRAG_RECEIVER_INFO) = 0x6c, 0x0, 0x5, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, 0x0, 0x0_NET_WM_NAME(UTF8_STRING) = myKeys.kdbx - KeePassXWM_CLIENT_LEADER(WINDOW): window id # 0x1c00005_NET_WM_PID(CARDINAL) = 26787_NET_WM_WINDOW_TYPE(ATOM) = _NET_WM_WINDOW_TYPE_NORMAL_MOTIF_WM_HINTS(_MOTIF_WM_HINTS) = 0x3, 0x3e, 0x7e, 0x0, 0x0WM_PROTOCOLS(ATOM): protocols  WM_DELETE_WINDOW, WM_TAKE_FOCUS, _NET_WM_PING, _NET_WM_SYNC_REQUESTWM_NAME(STRING) = Keys.kdbx - KeePassXWM_LOCALE_NAME(STRING) = en_US.UTF-8WM_CLASS(STRING) = keepassx, KeepassxWM_HINTS(WM_HINTS):        Client accepts input or input focus: True        Initial state is Normal State.        bitmap id # to use for icon: 0x1c0000b        window id # of group leader: 0x1c00005WM_NORMAL_HINTS(WM_SIZE_HINTS):        user specified location: 960, 22        program specified location: 960, 22        user specified size: 956 by 1033        program specified size: 956 by 1033        program specified minimum size: 640 by 517        window gravity: NorthWestWM_CLIENT_MACHINE(STRING) = nautilusWM_COMMAND(STRING) = { keepassx }I also tried the command   for_window [instance=keepassx] floating enablehow can I make the keepassX always stars in floating mode? 
Make KeepassX float in i3wm
configuration;i3;tiling wm
As Adaephon said, you just looked at the wrong string. Everything else should be fine.You want to distinct by class, so let's look at your xprop:WM_CLASS(STRING) = keepassx, KeepassxThis line is defined like:WM_CLASS(STRING) = instance, classAs you see, you wanted to float keepassx, but the class is KeepassxThere are two solutions for you:Use for_window [class=Keepassx] floating enable, as this refers to the right class name.Use for_window [class=(?i)keepassx] floating enable, which means that the searched string will be case-unsensitive.Bear in mind, that you can also use for_window with other attributes, like name, instance, etc.EDIT: I've read his comment again and yes, he should be right: Look again at your config to strike out that after that line, another one comes that may disable floating mode for specific or every windows.