git-gui: set suitable extended window manager hints.

This patch uses recent Tk attributes support to specify the intended use of new
toplevels by setting the correct EWMH hint. This helps modern window managers
to apply sensible decoration for the tooltip and dialogs.
Signed-off-by: NPat Thoyts <patthoyts@users.sourceforge.net>

lib/blame.tcl

@@ -1201,6 +1201,7 @@ method _open_tooltip {cur_w} {
 		_hide_tooltip $this
 
 		set tooltip_wm [toplevel $cur_w.tooltip -borderwidth 1]
+		catch {wm attributes $tooltip_wm -type tooltip}
 		wm overrideredirect $tooltip_wm 1
 		wm transient $tooltip_wm [winfo toplevel $cur_w]
 		set tooltip_t $tooltip_wm.label

lib/choose_rev.tcl

@@ -497,6 +497,7 @@ method _open_tooltip {} {
 
 	if {$tooltip_wm eq {}} {
 		set tooltip_wm [toplevel $w_list.tooltip -borderwidth 1]
+		catch {wm attributes $tooltip_wm -type tooltip}
 		wm overrideredirect $tooltip_wm 1
 		wm transient $tooltip_wm [winfo toplevel $w_list]
 		set tooltip_t $tooltip_wm.label

lib/class.tcl

@@ -138,6 +138,7 @@ proc make_dialog {t w args} {
 	upvar $t top $w pfx this this
 	global use_ttk
 	uplevel [linsert $args 0 make_toplevel $t $w]
+	catch {wm attributes $top -type dialog}
 	pave_toplevel $pfx
 }
 

lib/themed.tcl

@@ -123,6 +123,7 @@ proc paddedlabel {w args} {
 # place a themed frame over the surface.
 proc Dialog {w args} {
 	eval [linsert $args 0 toplevel $w -class Dialog]
+	catch {wm attributes $w -type dialog}	
 	pave_toplevel $w
 	return $w
 }

lib/transport.tcl

@@ -124,6 +124,7 @@ proc do_push_anywhere {} {
 
 	set w .push_setup
 	toplevel $w
+	catch {wm attributes $w -type dialog}
 	wm withdraw $w
 	wm geometry $w "+[winfo rootx .]+[winfo rooty .]"
 	pave_toplevel $w