gitk: TIP 474 based mouse wheel event handler

TIP 474 provides uniform way to handle mouse wheel events
for all platforms.

> TIP 474: Treat the mouse wheel events in a uniform way
> https://core.tcl-lang.org/tips/doc/trunk/tip/474.md

So, use Tk 9.0 mouse wheel event handler for all platforms.

Adjust horizontal scroll size from 5 to 1 for human eyes.
5 is too big.

Signed-off-by: YOKOTA Hiroshi <[email protected]>

Author: qykth-git

gitk

@@ -2702,40 +2702,40 @@ proc makewindow {} {
     pack .ctop -fill both -expand 1
     bindall <1> {selcanvline %W %x %y}
     #bindall <B1-Motion> {selcanvline %W %x %y}
-    switch -- [tk windowingsystem] {
-        "win32" {
-            bind .      <MouseWheel> { windows_mousewheel_redirector %W %X %Y %D }
-            bind $ctext <MouseWheel> { windows_mousewheel_redirector %W %X %Y %D }
+    global have_tk90
+    if {$have_tk90} {
+        bindall <MouseWheel> {
+            set delta [expr {((%D) >= 0) ? -5 : 5}]
+            allcanvs yview scroll $delta units
         }
-        "aqua" {
-            bindall <MouseWheel> {
-                set delta [expr {- (%D)}]
-                allcanvs yview scroll $delta units
-            }
-            bindall <Shift-MouseWheel> {
-                set delta [expr {- (%D)}]
-                $canv xview scroll $delta units
-            }
+        bindall <Shift-MouseWheel> {
+            set delta [expr {((%D) >= 0) ? -1 : 1}]
+            $canv xview scroll $delta units
         }
-        "x11" {
-            global have_tk90
-            if {$have_tk90} {
+    } else {
+        switch -- [tk windowingsystem] {
+            "win32" {
+                bind .      <MouseWheel> { windows_mousewheel_redirector %W %X %Y %D }
+                bind $ctext <MouseWheel> { windows_mousewheel_redirector %W %X %Y %D }
+            }
+            "aqua" {
                 bindall <MouseWheel> {
-                    set delta [expr {((%D) >= 0) ? -5 : 5}]
+                    set delta [expr {- (%D)}]
                     allcanvs yview scroll $delta units
                 }
                 bindall <Shift-MouseWheel> {
-                    set delta [expr {((%D) >= 0) ? -5 : 5}]
+                    set delta [expr {- (%D)}]
                     $canv xview scroll $delta units
                 }
-            } else {
+            }
+            "x11" {
                 bindall <ButtonRelease-4> "allcanvs yview scroll -5 units"
                 bindall <ButtonRelease-5> "allcanvs yview scroll  5 units"
                 bind $ctext <Button> {
                     if {"%b" eq 6} {
-                        $ctext xview scroll -5 units
+                        $ctext xview scroll -1 units
                     } elseif {"%b" eq 7} {
-                        $ctext xview scroll  5 units
+                        $ctext xview scroll  1 units
                     }
                 }
             }