There are a number of hidden options that cannot be set by the Xfce Settings Manager. These require use of a text editor.

The colors of the icon text and the icon text background, as well as the opacity of the icon text background and icon layout can be customized by putting directives similar to the following in your ~/.gtkrc-2.0 file:

style "xfdesktop-icon-view" {
    XfdesktopIconView::label-alpha = 75
    XfdesktopIconView::selected-label-alpha = 100
    XfdesktopIconView::ellipsize-icon-labels = 1
    XfdesktopIconView::tooltip-size = 128

    XfdesktopIconView::shadow-x-offset = 1
    XfdesktopIconView::shadow-y-offset = 1
    XfdesktopIconView::shadow-color = "#ff0000"
    XfdesktopIconView::selected-shadow-x-offset = 2
    XfdesktopIconView::selected-shadow-y-offset = 2
    XfdesktopIconView::selected-shadow-color = "#00ff00"

    XfdesktopIconView::cell-spacing = 6
    XfdesktopIconView::cell-padding = 6
    XfdesktopIconView::cell-text-width-proportion = 2.5

    base[NORMAL] = "#00ff00"
    base[SELECTED] = "#5050ff"
    base[ACTIVE] = "#0000ff"

    fg[NORMAL] = "#ff0000"
    fg[SELECTED] = "#ff0000"
    fg[ACTIVE] = "#ff0000"
}
widget_class "*XfdesktopIconView*" style "xfdesktop-icon-view"

The first four entries set the opacity of the rounded text background (allowed values are from 0 (totally transparent) to 255 (totally opaque), and whether or not unselected icons get their labels ellipsized (truncated) to fit on one line. (The 'selected-' version controls the opacity of icons that have been selected with the mouse.) The tooltip-size determines how large the image preview will be when the mouse is hovered over an icon (allowed values are from 0 (not shown) to 512, values larger than 256 may cause poor image quality however.)

The second six entries can be used to enable a text shadow to be painted with the icon labels. The offsets are in pixels. Setting them to 0 (the defaults) will disable the shadows entirely. Again, the 'selected-' versions apply to icons that have been selected with the mouse.

The third four entries set spacing and sizing for individual icons on the grid. The 'cell-spacing' property specifies the spacing between each 'cell' in the grid of icons. The 'cell-padding' property sets extra padding placed around each icon+text. The units for these two are in pixels. The 'cell-text-width-proportion' property specifies the maximum width of the text label underneat the icon, as a multiplier of the icon width (so for 30px icons, '2.5' would leave a 75px wide area underneath for the text).

The fourth three entries set the color of the rounded text background.

• NORMAL sets the color for the regular, unselected state.
• SELECTED sets the color for when the icon is selected, and the desktop has keyboard/mouse focus.
• ACTIVE sets the color for when the icon is selected, but the desktop does not have keyboard/mouse focus.

The final three entries set the color of the label text. See above for the differences between NORMAL, SELECTED, and ACTIVE.

There are a couple of hidden xfconf settings that cannot be set by the xfdesktop-settings application. The channel name that xfdesktop uses is 'xfce4-desktop'. For more information see the Xfconf Documentation.

/desktop-icons/right-click-edits-menu

Boolean, default is TRUE.

This value controls wether right clicking on a menu item pops up the Edit Launcher dialog.

/desktop-icons/center-text

Boolean, default is TRUE.

This value controls wether the text for all the desktop icons label are centered.

/desktop-menu/max-template-files

Integer, default value is 16.

This value controls how many items will appear in the Create From Template submenu.

The entire list of xfconf options for Xfdesktop can be found at README.xfconf.