git-gui: use themed tk widgets with Tk 8.5

This patch enables the use of themed Tk widgets with Tk 8.5 and above.
These make a significant difference on Windows in making the
application appear native. On Windows and MacOSX ttk defaults to the
native look as much as possible. On X11 the user may select a theme
using the TkTheme XRDB resource class by adding an line to the
.Xresources file. The set of installed theme names is available using
the Tk command 'ttk::themes'. The default on X11 is similar to the current
un-themed style - a kind of thin bordered motif look.

A new git config variable 'gui.usettk' may be set to disable this if
the user prefers the classic Tk look. Using Tk 8.4 will also avoid the
use of themed widgets as these are only available since 8.5.

Some support is included for Tk 8.6 features (themed spinbox and native
font chooser for MacOSX and Windows).

Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

lib/choose_font.tcl

@@ -17,6 +17,7 @@ variable all_families [list]  ; # All fonts known to Tk
 
 constructor pick {path title a_family a_size} {
 	variable all_families
+	global use_ttk NS
 
 	set v_family $a_family
 	set v_size $a_size
@@ -27,29 +28,30 @@ constructor pick {path title a_family a_size} {
 	set f_family $pv_family
 	set f_size $pv_size
 
-	make_toplevel top w
+	make_dialog top w
+	wm withdraw $top
 	wm title $top "[appname] ([reponame]): $title"
 	wm geometry $top "+[winfo rootx $path]+[winfo rooty $path]"
 
-	label $w.header -text $title -font font_uibold
+	${NS}::label $w.header -text $title -font font_uibold -anchor center
 	pack $w.header -side top -fill x
 
-	frame $w.buttons
-	button $w.buttons.select \
+	${NS}::frame $w.buttons
+	${NS}::button $w.buttons.select \
 		-text [mc Select] \
 		-default active \
 		-command [cb _select]
-	button $w.buttons.cancel \
+	${NS}::button $w.buttons.cancel \
 		-text [mc Cancel] \
 		-command [list destroy $w]
 	pack $w.buttons.select -side right
 	pack $w.buttons.cancel -side right -padx 5
 	pack $w.buttons -side bottom -fill x -pady 10 -padx 10
 
-	frame $w.inner
+	${NS}::frame $w.inner
 
-	frame $w.inner.family
-	label $w.inner.family.l \
+	${NS}::frame $w.inner.family
+	${NS}::label $w.inner.family.l \
 		-text [mc "Font Family"] \
 		-anchor w
 	set w_family $w.inner.family.v
@@ -64,16 +66,16 @@ constructor pick {path title a_family a_size} {
 		-height 10 \
 		-yscrollcommand [list $w.inner.family.sby set]
 	rmsel_tag $w_family
-	scrollbar $w.inner.family.sby -command [list $w_family yview]
+	${NS}::scrollbar $w.inner.family.sby -command [list $w_family yview]
 	pack $w.inner.family.l -side top -fill x
 	pack $w.inner.family.sby -side right -fill y
 	pack $w_family -fill both -expand 1
 
-	frame $w.inner.size
-	label $w.inner.size.l \
+	${NS}::frame $w.inner.size
+	${NS}::label $w.inner.size.l \
 		-text [mc "Font Size"] \
 		-anchor w
-	spinbox $w.inner.size.v \
+	tspinbox $w.inner.size.v \
 		-textvariable @f_size \
 		-from 2 -to 80 -increment 1 \
 		-width 3
@@ -86,8 +88,8 @@ constructor pick {path title a_family a_size} {
 	grid columnconfigure $w.inner 0 -weight 1
 	pack $w.inner -fill both -expand 1 -padx 5 -pady 5
 
-	frame $w.example
-	label $w.example.l \
+	${NS}::frame $w.example
+	${NS}::label $w.example.l \
 		-text [mc "Font Example"] \
 		-anchor w
 	set w_example $w.example.t
@@ -129,6 +131,7 @@ constructor pick {path title a_family a_size} {
 		grab $w
 		focus $w
 	"
+	wm deiconify $w
 	tkwait window $w
 }