Reordering a bit.

Project/scripts/button_set/button_set.gml

@@ -0,0 +1,39 @@
+///button_set(x_, y_, type)
+
+x_ = argument0;
+y_ = argument1;
+type = argument2;
+
+image_speed = 0;
+
+length = 0.25;
+scale = global.icon_scale;
+color = c_white;
+halign = fa_center;
+valign = fa_middle;
+
+switch(type)
+{
+    case but.plus:
+        text = "+";
+        image_index = 4;
+        scale = global.icon_scale * 1.5;
+        
+        x_ = button_align_x(region.mid_right, 1.5);
+        y_ = button_align_y(region.mid_right, 0);
+    break;
+    
+    case but.minus:
+        text = "-";
+        image_index = 4;
+        
+        x_ = button_align_x(region.mid_right, -1.5);
+        y_ = button_align_y(region.mid_right, 0);
+    break;
+};
+
+x = x_;
+y = y_;
+
+width =  sprite_get_width(sprite_index)  * scale * length;
+height = sprite_get_height(sprite_index) * scale;

Project/scripts/button_set/button_set.yy

@@ -0,0 +1,8 @@
+{
+    "id": "51d00fa8-eb85-4086-a732-a161d9d217d8",
+    "modelName": "GMScript",
+    "mvc": "1.0",
+    "name": "button_set",
+    "IsCompatibility": false,
+    "IsDnD": false
+}