git-gui: Remove unnecessary space between columns in blame viewer

On Mac OS X the OS has "features" that like to draw thick black
borders around the text field that has focus.  This is nice if
you want to know where your text is going and are blind as a bat,
but it isn't the best thing to have in a table that is being
faked through the abuse of Tk text widgets.

By setting our takefocus, highlightthickness and padx/y we can
get rid of this border and get our text widgets packed right next
to each other, with no padding between them.  This makes the blame
background color smoothly run across the entire line of commit data,
line number and file content.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

lib/blame.tcl

@@ -114,16 +114,22 @@ constructor new {i_commit i_path} {
 
 	set w_line $w.file_pane.out.linenumber_t
 	text $w_line \
+		-takefocus 0 \
+		-highlightthickness 0 \
+		-padx 0 -pady 0 \
 		-background white -borderwidth 0 \
 		-state disabled \
 		-wrap none \
 		-height 40 \
 		-width 5 \
 		-font font_diff
-	$w_line tag conf linenumber -justify right
+	$w_line tag conf linenumber -justify right -rmargin 5
 
 	set w_cgrp $w.file_pane.out.commit_t
 	text $w_cgrp \
+		-takefocus 0 \
+		-highlightthickness 0 \
+		-padx 0 -pady 0 \
 		-background white -borderwidth 0 \
 		-state disabled \
 		-wrap none \
@@ -140,6 +146,9 @@ constructor new {i_commit i_path} {
 
 	set w_file $w.file_pane.out.file_t
 	text $w_file \
+		-takefocus 0 \
+		-highlightthickness 0 \
+		-padx 0 -pady 0 \
 		-background white -borderwidth 0 \
 		-state disabled \
 		-wrap none \