/usr/local/share/applications/dhcpcd-gtk.desktop comes with dhcpcd from base

Just installed 0.75.2. Same issue and error messages as already reported here in ... March 2015. Does not work for me.

dhcpcd-ui works with GTK3. Shouldn't the dependency be bumped?

Have you tested with the latest upstream version 0.7.5? The AUR package has been flagged out of date.

I got the following error when trying to launch it:
** Message: Connecting ...
** Message: Status changed to down
** (dhcpcd-gtk:4497): CRITICAL **: dhcpcd_open: No such file or directory

Even though I already had connected to my network using dhcpcd at bootup time I ran dhcpcd (as root as the program told me to do) and got:
dhcpcd[4543]: version 6.7.1 starting
dhcpcd[4543]: DUID 00:01:00:01:1c:29:88:5a:60:a4:4c:b4:5d:cc
dhcpcd[4543]: eno1: IAID 4c:b4:5d:cc
** Message: Status changed to opened
** Message: Connected to dhcpcd-6.7.1
** Message: Status changed to connecting
** Message: eno1: Cable plugged in
dhcpcd[4543]: eno1: soliciting an IPv6 router
dhcpcd[4543]: eno1: rebinding lease of 192.168.7.100
dhcpcd[4543]: eno1: changing route to 192.168.7.0/24
dhcpcd[4543]: eno1: changing default route via 192.168.7.1
dhcpcd[4543]: forked to background, child pid 4555

After that I run dhcpcd-gtk again and got:
** Message: Connecting ...
** Message: Status changed to down
** Message: Status changed to opened
** Message: Connected to dhcpcd-6.7.1
** Message: Status changed to connected
** Message: eno1: CARRIER
** Message: eno1: Configured 192.168.7.100/24

But no window opened!
Is this a problem with the package and someone can confirm this or is it a problem with my config and I should ask in the forum / elsewhere?

Also, on the website notification-daemon-0.3.7 is said to be an optional dependency, is this libnotify here and should it be made optional or should sth. like notification-daemon-gtk2 be added to the dependencies?

The PKGBUILD for 0.6.0-1 is placing it icons in the wrong directory and placing its autostart file in the wrong directory. You need to change the ./configure line to:

./configure --prefix=/usr --icondir=/usr/share/icons

There also needs to be an .install script to update the icon cache.

You need to change the make install line to:

make DESTDIR="$pkgdir" AUTOSTARTDIR=/etc/xdg/autostart install

to get the autostart file in the right location.

Also the license file is missing: it can be stripped from the top of any of the .c files.

I will send you a .src package that has these corrections.