[PATCH v2] git-gui: Error on systems with TK < 8.6.0

[Peter van der Does]

Using git-gui on systems that run a TK version below 8.6.0 results in a
crash when checking for the current theme.

Catch the error on those systems and use a different command to check
for the current theme.

Signed-off-by: Peter van der Does <pe...@avirtualhome.com>
---
 lib/themed.tcl | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/themed.tcl b/lib/themed.tcl
index 351a712..bb4e8f2 100644
--- a/lib/themed.tcl
+++ b/lib/themed.tcl
@@ -248,7 +248,11 @@ proc tspinbox {w args} {
 proc ttext {w args} {
        global use_ttk
        if {$use_ttk} {
-               switch -- [ttk::style theme use] {
+               # Handle either current Tk or older versions of 8.5
+               if {[catch {set theme [ttk::style theme use]}]} {
+                       set theme  $::ttk::currentTheme
+               }
+               switch -- $theme {
                        "vista" - "xpnative" {
                                lappend args -highlightthickness 0 -borderwidth 0
                        }
-- 
2.12.2