How to change zzzFM and pcmanfm backgroud color

1. Install human-icon-theme

sudo apt install human-icon-theme

2. Make a custom theme folder and config file

sudo mkdir -p /usr/share/themes/Custom/gtk-2.0

gksu leafpad /usr/share/themes/Custom/gtk-2.0/gtkrc

… which contents is

# Edit these colors and fonts however you like.
style "default"
{
GtkOptionMenu::indicator_spacing = { 3, 2, 1, 1 }
GtkEntry::progress-border = { 1, 1, 1, 1 }
GtkRange::slider_width = 11
GtkRange::stepper_size = 11
GtkScrollbar::min_slider_length = 14
GtkCheckButton::indicator_size = 10
GtkCheckMenuItem::indicator_size = 10
GtkButton::default_border = { 0, 0, 0, 0 }

fg[NORMAL] = "#000000"
fg[ACTIVE] = "#000000"
fg[PRELIGHT] = "#000000"
fg[SELECTED] = "#FFFFFF"
fg[INSENSITIVE] = "#747474"
bg[NORMAL] = "#d8c580"
bg[ACTIVE] = "#C1C1CC"
bg[PRELIGHT] = "#a8d0be"
bg[SELECTED] = "#336699"
bg[INSENSITIVE] = "#d8c580"
base[NORMAL] = "#a8d0be"
base[ACTIVE] = "#808080"
base[PRELIGHT] = "#a8d0be"
base[SELECTED] = "#336699"
base[INSENSITIVE] = "#a8d0be"
text[NORMAL] = "#000000"
text[ACTIVE] = "#FFFFFF"
text[PRELIGHT] = "#000000"
text[SELECTED] = "#FFFFFF"
text[INSENSITIVE] = "#747474"

#font_name = "Sans 10"
engine "thinice"
{
# Do you want the scrollbar handles rectangular or a bit shaped?
rect_scrollbar = FALSE

# The following variables are semi-generic, can be applied to
# different widget classes etc..

# Mark type 1 is used on scrollbar handles, handleboxes etc
# Can be: NOTHING, SLASH, INVSLASH, DOT, INVDOT
mark_type1 = SLASH

# Mark type 2 is used on scrollbar buttons
# Can be: NOTHING, SLASH, INVSLASH, DOT, INVDOT, ARROW
mark_type2 = ARROW

# How to draw paned stuff
# Can be: NONE, SOME (currently 5), FULL
paned_dots = SOME
}
}

style "tooltips" {
bg[NORMAL] = "#EEE1B3"
fg[NORMAL] = "#000000"
}

style "progress-bar" {
bg[PRELIGHT] = "#336699"
fg[PRELIGHT] = "#FFFFFF"
bg[NORMAL] = "#C1C1CC"
}

style "menu-item" {
bg[PRELIGHT] = "#C9D2F5"
fg[PRELIGHT] = "#FFFFFF"
base[PRELIGHT] = "#336699"
text[PRELIGHT] = "#FFFFFF"
}

style "entry" {
bg[SELECTED] = "#C9D2F5"
fg[SELECTED] = "#000000"
}

class "GtkWidget" style "default"
widget "gtk-tooltip*" style "tooltips"
class "GtkProgressBar" style "progress-bar"
class "*MenuItem*" style "menu-item"
class "GtkEntry" style "entry"
widget_class "*MenuItem*" style "menu-item"
widget_class "*.GtkAccelMenuItem.*" style "menu-item"
widget_class "*.GtkRadioMenuItem.*" style "menu-item"
widget_class "*.GtkCheckMenuItem.*" style "menu-item"
widget_class "*.GtkImageMenuItem.*" style "menu-item"
widget_class "*.GtkSeparatorMenuItem.*" style "menu-item"
widget_class "*.GtkRadioMenuItem.*" style "menu-item"

gtk-icon-theme-name="Human"

… save and quit

3. Edit /usr/share/applications/zzzfm.desktop file replacing

Exec=zzzfm %F

as

Exec=env GTK2_RC_FILES=/usr/share/themes/Custom/gtk-2.0/gtkrc zzzfm

gksu leafpad /usr/share/applications/zzzfm.desktop

The result

With Pcmanfm /usr/share/applications/pcmanfm.desktop exec-line must be

Exec=env GTK2_RC_FILES=/usr/share/themes/Custom/gtk-2.0/gtkrc pcmanfm