diff --git a/basis/ui/gadgets/theme/dark/dark.factor b/basis/ui/gadgets/theme/dark/dark.factor
index ea2d4d19df..a14b2d1500 100644
--- a/basis/ui/gadgets/theme/dark/dark.factor
+++ b/basis/ui/gadgets/theme/dark/dark.factor
@@ -1,87 +1,88 @@
 ! Copyright (C) 2016 Nicolas Pénet.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: accessors colors colors.constants colors.hex ui.pens.solid ;
-IN: ui.gadgets.theme
+USING: accessors colors colors.constants colors.hex
+ui.gadgets.theme ui.pens.solid ;
+IN: ui.gadgets.theme.dark
 
-CONSTANT: toolbar-background COLOR: solarized-base02
-CONSTANT: toolbar-button-pressed-background COLOR: solarized-base0
+M: dark toolbar-background COLOR: solarized-base02 ;
+M: dark toolbar-button-pressed-background COLOR: solarized-base0 ;
 
-CONSTANT: menu-background COLOR: solarized-base02
-CONSTANT: menu-border-color COLOR: solarized-base01
+M: dark menu-background COLOR: solarized-base02 ;
+M: dark menu-border-color COLOR: solarized-base01 ;
 
-CONSTANT: status-bar-background COLOR: FactorDarkSlateBlue
-CONSTANT: status-bar-foreground COLOR: white
+M: dark status-bar-background COLOR: FactorDarkSlateBlue ;
+M: dark status-bar-foreground COLOR: white ;
 
-CONSTANT: button-text-color COLOR: solarized-base1
-CONSTANT: button-clicked-text-color COLOR: white
+M: dark button-text-color COLOR: solarized-base1 ;
+M: dark button-clicked-text-color COLOR: white ;
 
-CONSTANT: line-color COLOR: solarized-base01
+M: dark line-color COLOR: solarized-base01 ;
 
-CONSTANT: column-title-background COLOR: solarized-base01
+M: dark column-title-background COLOR: solarized-base01 ;
 
-CONSTANT: roll-button-rollover-border COLOR: gray50
-CONSTANT: roll-button-selected-background COLOR: dark-gray
+M: dark roll-button-rollover-border COLOR: gray50 ;
+M: dark roll-button-selected-background COLOR: dark-gray ;
 
-CONSTANT: source-files-color COLOR: solarized-green
-CONSTANT: errors-color COLOR: solarized-red
-CONSTANT: details-color COLOR: solarized-blue
+M: dark source-files-color COLOR: solarized-green ;
+M: dark errors-color COLOR: solarized-red ;
+M: dark details-color COLOR: solarized-blue ;
 
-CONSTANT: debugger-color COLOR: solarized-red
-CONSTANT: completion-color COLOR: solarized-violet
+M: dark debugger-color COLOR: solarized-red ;
+M: dark completion-color COLOR: solarized-violet ;
 
-CONSTANT: data-stack-color COLOR: solarized-blue
-CONSTANT: retain-stack-color COLOR: solarized-magenta
-CONSTANT: call-stack-color COLOR: solarized-green
+M: dark data-stack-color COLOR: solarized-blue ;
+M: dark retain-stack-color COLOR: solarized-magenta ;
+M: dark call-stack-color COLOR: solarized-green ;
 
-CONSTANT: title-bar-gradient { COLOR: solarized-base01 COLOR: solarized-base02 }
+M: dark title-bar-gradient { COLOR: solarized-base01 COLOR: solarized-base02 } ;
 
-CONSTANT: popup-color COLOR: solarized-yellow
+M: dark popup-color COLOR: solarized-yellow ;
 
-CONSTANT: object-color COLOR: solarized-cyan
-CONSTANT: contents-color COLOR: solarized-magenta
+M: dark object-color COLOR: solarized-cyan ;
+M: dark contents-color COLOR: solarized-magenta ;
 
-CONSTANT: help-header-background HEXCOLOR: 2F4D5B
+M: dark help-header-background HEXCOLOR: 2F4D5B ;
 
-CONSTANT: thread-status-stopped-background HEXCOLOR: 492d33
-CONSTANT: thread-status-suspended-background HEXCOLOR: 3c4a24
-CONSTANT: thread-status-running-background HEXCOLOR: 2c4f24
+M: dark thread-status-stopped-background HEXCOLOR: 492d33 ;
+M: dark thread-status-suspended-background HEXCOLOR: 3c4a24 ;
+M: dark thread-status-running-background HEXCOLOR: 2c4f24 ;
 
-CONSTANT: thread-status-stopped-foreground COLOR: solarized-red
-CONSTANT: thread-status-suspended-foreground COLOR: solarized-yellow
-CONSTANT: thread-status-running-foreground COLOR: solarized-green
+M: dark thread-status-stopped-foreground COLOR: solarized-red ;
+M: dark thread-status-suspended-foreground COLOR: solarized-yellow ;
+M: dark thread-status-running-foreground COLOR: solarized-green ;
 
-CONSTANT: error-summary-background HEXCOLOR: 6E2E32
+M: dark error-summary-background HEXCOLOR: 6E2E32 ;
 
-CONSTANT: content-background COLOR: solarized-base03
-CONSTANT: text-color COLOR: grey75
+M: dark content-background COLOR: solarized-base03 ;
+M: dark text-color COLOR: grey75 ;
 
-CONSTANT: link-color COLOR: solarized-blue
-CONSTANT: url-color COLOR: solarized-blue
-CONSTANT: title-color COLOR: grey75
-CONSTANT: heading-color COLOR: grey75
-CONSTANT: snippet-color COLOR: solarized-orange
-CONSTANT: output-color COLOR: solarized-orange
-CONSTANT: warning-background-color HEXCOLOR: 6E2E32
-CONSTANT: code-background-color HEXCOLOR: 2F4D5B
+M: dark link-color COLOR: solarized-blue ;
+M: dark url-color COLOR: solarized-blue ;
+M: dark title-color COLOR: grey75 ;
+M: dark heading-color COLOR: grey75 ;
+M: dark snippet-color COLOR: solarized-orange ;
+M: dark output-color COLOR: solarized-orange ;
+M: dark warning-background-color HEXCOLOR: 6E2E32 ;
+M: dark code-background-color HEXCOLOR: 2F4D5B ;
 
-CONSTANT: tip-background-color HEXCOLOR: 2F4D5B
+M: dark tip-background-color HEXCOLOR: 2F4D5B ;
 
-CONSTANT: prompt-background-color HEXCOLOR: 922f31
+M: dark prompt-background-color HEXCOLOR: 922f31 ;
 
-CONSTANT: dim-color COLOR: solarized-cyan
-CONSTANT: highlighted-word-color COLOR: solarized-green
-CONSTANT: string-color COLOR: solarized-magenta
-CONSTANT: stack-effect-color COLOR: solarized-orange
+M: dark dim-color COLOR: solarized-cyan ;
+M: dark highlighted-word-color COLOR: solarized-green ;
+M: dark string-color COLOR: solarized-magenta ;
+M: dark stack-effect-color COLOR: solarized-orange ;
 
-CONSTANT: vocab-background-color COLOR: solarized-base01
-CONSTANT: vocab-border-color COLOR: solarized-base01
+M: dark vocab-background-color COLOR: solarized-base01 ;
+M: dark vocab-border-color COLOR: solarized-base01 ;
 
-CONSTANT: field-border-color COLOR: solarized-base01
+M: dark field-border-color COLOR: solarized-base01 ;
 
-CONSTANT: selection-color COLOR: solarized-base01
+M: dark selection-color COLOR: solarized-base01 ;
 
-CONSTANT: panel-background-color T{ rgba f 0.7843 0.7686 0.7176 1.0 }
+M: dark panel-background-color T{ rgba f 0.7843 0.7686 0.7176 1.0 } ;
 
-CONSTANT: focus-border-color COLOR: solarized-base01
+M: dark focus-border-color COLOR: solarized-base01 ;
 
-CONSTANT: labeled-border-color COLOR: grey85
+M: dark labeled-border-color COLOR: grey85 ;
diff --git a/basis/ui/gadgets/theme/light/light.factor b/basis/ui/gadgets/theme/light/light.factor
index 83cf0652da..3cbfecc80e 100644
--- a/basis/ui/gadgets/theme/light/light.factor
+++ b/basis/ui/gadgets/theme/light/light.factor
@@ -1,87 +1,88 @@
 ! Copyright (C) 2015 Nicolas Pénet.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: accessors colors colors.constants colors.hex ui.pens.solid ;
-IN: ui.gadgets.theme
+USING: accessors colors colors.constants colors.hex
+ui.gadgets.theme ui.pens.solid ;
+IN: ui.gadgets.theme.light
 
-CONSTANT: toolbar-background COLOR: grey95
-CONSTANT: toolbar-button-pressed-background COLOR: dark-gray
+M: light toolbar-background COLOR: grey95 ;
+M: light toolbar-button-pressed-background COLOR: dark-gray ;
 
-CONSTANT: menu-background COLOR: grey95
-CONSTANT: menu-border-color COLOR: grey75
+M: light menu-background COLOR: grey95 ;
+M: light menu-border-color COLOR: grey75 ;
 
-CONSTANT: status-bar-background COLOR: FactorDarkSlateBlue
-CONSTANT: status-bar-foreground COLOR: white
+M: light status-bar-background COLOR: FactorDarkSlateBlue ;
+M: light status-bar-foreground COLOR: white ;
 
-CONSTANT: button-text-color COLOR: FactorDarkSlateBlue
-CONSTANT: button-clicked-text-color COLOR: white
+M: light button-text-color COLOR: FactorDarkSlateBlue ;
+M: light button-clicked-text-color COLOR: white ;
 
-CONSTANT: line-color COLOR: grey75
+M: light line-color COLOR: grey75 ;
 
-CONSTANT: column-title-background COLOR: grey95
+M: light column-title-background COLOR: grey95 ;
 
-CONSTANT: roll-button-rollover-border COLOR: gray50
-CONSTANT: roll-button-selected-background COLOR: dark-gray
+M: light roll-button-rollover-border COLOR: gray50 ;
+M: light roll-button-selected-background COLOR: dark-gray ;
 
-CONSTANT: source-files-color COLOR: MediumSeaGreen
-CONSTANT: errors-color COLOR: chocolate1
-CONSTANT: details-color COLOR: SteelBlue3
+M: light source-files-color COLOR: MediumSeaGreen ;
+M: light errors-color COLOR: chocolate1 ;
+M: light details-color COLOR: SteelBlue3 ;
 
-CONSTANT: debugger-color COLOR: chocolate1
-CONSTANT: completion-color COLOR: magenta
+M: light debugger-color COLOR: chocolate1 ;
+M: light completion-color COLOR: magenta ;
 
-CONSTANT: data-stack-color COLOR: DodgerBlue
-CONSTANT: retain-stack-color COLOR: HotPink
-CONSTANT: call-stack-color COLOR: GreenYellow
+M: light data-stack-color COLOR: DodgerBlue ;
+M: light retain-stack-color COLOR: HotPink ;
+M: light call-stack-color COLOR: GreenYellow ;
 
-CONSTANT: title-bar-gradient { COLOR: white COLOR: grey90 }
+M: light title-bar-gradient { COLOR: white COLOR: grey90 } ;
 
-CONSTANT: popup-color COLOR: yellow2
+M: light popup-color COLOR: yellow2 ;
 
-CONSTANT: object-color COLOR: aquamarine2
-CONSTANT: contents-color COLOR: orchid2
+M: light object-color COLOR: aquamarine2 ;
+M: light contents-color COLOR: orchid2 ;
 
-CONSTANT: help-header-background HEXCOLOR: F4EFD9
+M: light help-header-background HEXCOLOR: F4EFD9 ;
 
-CONSTANT: thread-status-stopped-background HEXCOLOR: F4D9D9
-CONSTANT: thread-status-suspended-background HEXCOLOR: F4EAD9
-CONSTANT: thread-status-running-background HEXCOLOR: EDF4D9
+M: light thread-status-stopped-background HEXCOLOR: F4D9D9 ;
+M: light thread-status-suspended-background HEXCOLOR: F4EAD9 ;
+M: light thread-status-running-background HEXCOLOR: EDF4D9 ;
 
-CONSTANT: thread-status-stopped-foreground HEXCOLOR: F42300
-CONSTANT: thread-status-suspended-foreground HEXCOLOR: F37B00
-CONSTANT: thread-status-running-foreground HEXCOLOR: 3FCA00
+M: light thread-status-stopped-foreground HEXCOLOR: F42300 ;
+M: light thread-status-suspended-foreground HEXCOLOR: F37B00 ;
+M: light thread-status-running-foreground HEXCOLOR: 3FCA00 ;
 
-CONSTANT: error-summary-background HEXCOLOR: F4D9D9
+M: light error-summary-background HEXCOLOR: F4D9D9 ;
 
-CONSTANT: content-background COLOR: white
-CONSTANT: text-color COLOR: black
+M: light content-background COLOR: white ;
+M: light text-color COLOR: black ;
 
-CONSTANT: link-color COLOR: DodgerBlue4
-CONSTANT: url-color COLOR: DodgerBlue4
-CONSTANT: title-color COLOR: gray20
-CONSTANT: heading-color COLOR: FactorDarkSlateBlue
-CONSTANT: snippet-color COLOR: DarkOrange4
-CONSTANT: output-color COLOR: DarkOrange4
-CONSTANT: warning-background-color COLOR: gray90
-CONSTANT: code-background-color COLOR: FactorLightTan
+M: light link-color COLOR: DodgerBlue4 ;
+M: light url-color COLOR: DodgerBlue4 ;
+M: light title-color COLOR: gray20 ;
+M: light heading-color COLOR: FactorDarkSlateBlue ;
+M: light snippet-color COLOR: DarkOrange4 ;
+M: light output-color COLOR: DarkOrange4 ;
+M: light warning-background-color COLOR: gray90 ;
+M: light code-background-color COLOR: FactorLightTan ;
 
-CONSTANT: tip-background-color COLOR: lavender
+M: light tip-background-color COLOR: lavender ;
 
-CONSTANT: prompt-background-color T{ rgba f 1 0.7 0.7 1 }
+M: light prompt-background-color T{ rgba f 1 0.7 0.7 1 } ;
 
-CONSTANT: dim-color COLOR: gray35
-CONSTANT: highlighted-word-color COLOR: DarkSlateGray
-CONSTANT: string-color COLOR: LightSalmon4
-CONSTANT: stack-effect-color COLOR: FactorDarkGreen
+M: light dim-color COLOR: gray35 ;
+M: light highlighted-word-color COLOR: DarkSlateGray ;
+M: light string-color COLOR: LightSalmon4 ;
+M: light stack-effect-color COLOR: FactorDarkGreen ;
 
-CONSTANT: vocab-background-color COLOR: FactorLightTan
-CONSTANT: vocab-border-color COLOR: FactorDarkTan
+M: light vocab-background-color COLOR: FactorLightTan ;
+M: light vocab-border-color COLOR: FactorDarkTan ;
 
-CONSTANT: field-border-color COLOR: gray
+M: light field-border-color COLOR: gray ;
 
-CONSTANT: selection-color T{ rgba f 0.8 0.8 1.0 1.0 }
+M: light selection-color T{ rgba f 0.8 0.8 1.0 1.0 } ;
 
-CONSTANT: panel-background-color T{ rgba f 0.7843 0.7686 0.7176 1.0 }
+M: light panel-background-color T{ rgba f 0.7843 0.7686 0.7176 1.0 } ;
 
-CONSTANT: focus-border-color COLOR: dark-gray
+M: light focus-border-color COLOR: dark-gray ;
 
-CONSTANT: labeled-border-color COLOR: grey85
+M: light labeled-border-color COLOR: grey85 ;
diff --git a/basis/ui/gadgets/theme/switching/switching.factor b/basis/ui/gadgets/theme/switching/switching.factor
new file mode 100644
index 0000000000..a418beae57
--- /dev/null
+++ b/basis/ui/gadgets/theme/switching/switching.factor
@@ -0,0 +1,26 @@
+! Copyright (C) 2009, 2010 Slava Pestov, Joe Groff.
+! See http://factorcode.org/license.txt for BSD license.
+USING: fry hashtables help.stylesheet io.styles kernel
+namespaces ui.gadgets.theme ;
+IN: ui.gadgets.theme.switching
+
+: (update-style) ( style color elt -- )
+    '[ _ _ rot ?set-at ] change-global ;
+
+: update-stylesheet ( -- )
+    default-span-style text-color foreground (update-style)
+    link-style link-color foreground (update-style)
+    title-style title-color foreground (update-style)
+    heading-style heading-color foreground (update-style)
+    snippet-style snippet-color foreground (update-style)
+    code-style code-background-color page-color (update-style)
+    output-style output-color foreground (update-style)
+    url-style url-color foreground (update-style)
+    warning-style warning-background-color page-color (update-style)
+    deprecated-style warning-background-color page-color (update-style)
+    table-style line-color table-border (update-style) ;
+
+: light-theme ( -- ) light new theme set-global update-stylesheet ;
+: dark-theme ( -- ) dark new theme set-global update-stylesheet ;
+
+light-theme
diff --git a/basis/ui/gadgets/theme/theme.factor b/basis/ui/gadgets/theme/theme.factor
index b618fdff1a..70d3d84eb0 100644
--- a/basis/ui/gadgets/theme/theme.factor
+++ b/basis/ui/gadgets/theme/theme.factor
@@ -6,4 +6,91 @@ IN: ui.gadgets.theme
 : theme-image ( name -- image-name )
     "vocab:ui/gadgets/theme/" prepend-path ".tiff" append <image-name> ;
 
-<< "ui.gadgets.theme.light" require >>
+SYMBOL: theme
+TUPLE: light ;
+TUPLE: dark ;
+
+light new theme set-global
+
+HOOK: toolbar-background theme ( -- color )
+HOOK: toolbar-button-pressed-background theme ( -- color )
+
+HOOK: menu-background theme ( -- color )
+HOOK: menu-border-color theme ( -- color )
+
+HOOK: status-bar-background theme ( -- color )
+HOOK: status-bar-foreground theme ( -- color )
+
+HOOK: button-text-color theme ( -- color )
+HOOK: button-clicked-text-color theme ( -- color )
+
+HOOK: line-color theme ( -- color )
+
+HOOK: column-title-background theme ( -- color )
+
+HOOK: roll-button-rollover-border theme ( -- color )
+HOOK: roll-button-selected-background theme ( -- color )
+
+HOOK: source-files-color theme ( -- color )
+HOOK: errors-color theme ( -- color )
+HOOK: details-color theme ( -- color )
+
+HOOK: debugger-color theme ( -- color )
+HOOK: completion-color theme ( -- color )
+
+HOOK: data-stack-color theme ( -- color )
+HOOK: retain-stack-color theme ( -- color )
+HOOK: call-stack-color theme ( -- color )
+
+HOOK: title-bar-gradient theme ( -- color )
+
+HOOK: popup-color theme ( -- color )
+
+HOOK: object-color theme ( -- color )
+HOOK: contents-color theme ( -- color )
+
+HOOK: help-header-background theme ( -- color )
+
+HOOK: thread-status-stopped-background theme ( -- color )
+HOOK: thread-status-suspended-background theme ( -- color )
+HOOK: thread-status-running-background theme ( -- color )
+
+HOOK: thread-status-stopped-foreground theme ( -- color )
+HOOK: thread-status-suspended-foreground theme ( -- color )
+HOOK: thread-status-running-foreground theme ( -- color )
+
+HOOK: error-summary-background theme ( -- color )
+
+HOOK: content-background theme ( -- color )
+HOOK: text-color theme ( -- color )
+
+HOOK: link-color theme ( -- color )
+HOOK: url-color theme ( -- color )
+HOOK: title-color theme ( -- color )
+HOOK: heading-color theme ( -- color )
+HOOK: snippet-color theme ( -- color )
+HOOK: output-color theme ( -- color )
+HOOK: warning-background-color theme ( -- color )
+HOOK: code-background-color theme ( -- color )
+
+HOOK: tip-background-color theme ( -- color )
+
+HOOK: prompt-background-color theme ( -- color )
+
+HOOK: dim-color theme ( -- color )
+HOOK: highlighted-word-color theme ( -- color )
+HOOK: string-color theme ( -- color )
+HOOK: stack-effect-color theme ( -- color )
+
+HOOK: vocab-background-color theme ( -- color )
+HOOK: vocab-border-color theme ( -- color )
+
+HOOK: field-border-color theme ( -- color )
+
+HOOK: selection-color theme ( -- color )
+
+HOOK: panel-background-color theme ( -- color )
+
+HOOK: focus-border-color theme ( -- color )
+
+HOOK: labeled-border-color theme ( -- color )