diff --git a/RELEASE-NOTES.md b/RELEASE-NOTES.md
index 96812b762..c6a82c298 100755
--- a/RELEASE-NOTES.md
+++ b/RELEASE-NOTES.md
@@ -1,5 +1,16 @@
 ## RELEASE NOTES
 
+### Version 2.3.4 - Aug xx, 2018
+
+**Enhancements**
+
+- **Modal/Dimmer** - Modals and dimmers now include a new setting `useFlex` which defaults to `auto`. Modals and dimmers will automatically revert to using non-flex layouts when there may be layout issues with using flexbox.
+
+For example when `attachable: false` is used with a modal, or if IE11/Edge is used (Absolutely positioned elements inside flex containers in IE behave differently)
+
+
+
+
 ### Version 2.3.3 - June 18, 2018
 
 **Bug Fixes**
diff --git a/src/definitions/modules/dimmer.js b/src/definitions/modules/dimmer.js
index bdfc39abb..f622e925a 100755
--- a/src/definitions/modules/dimmer.js
+++ b/src/definitions/modules/dimmer.js
@@ -243,12 +243,22 @@ $.fn.dimmer = function(parameters) {
               : function(){}
             ;
             if(settings.useCSS && $.fn.transition !== undefined && $dimmer.transition('is supported')) {
+              if(settings.useFlex) {
+                module.debug('Using flex dimmer');
+                module.remove.legacy();
+              }
+              else {
+                module.debug('Using legacy non-flex dimmer');
+                module.set.legacy();
+              }
               if(settings.opacity !== 'auto') {
                 module.set.opacity();
               }
               $dimmer
                 .transition({
-                  displayType : 'flex',
+                  displayType : settings.useFlex
+                    ? 'flex'
+                    : 'block',
                   animation   : settings.transition + ' in',
                   queue       : false,
                   duration    : module.get.duration(),
@@ -293,7 +303,9 @@ $.fn.dimmer = function(parameters) {
               module.verbose('Hiding dimmer with css');
               $dimmer
                 .transition({
-                  displayType : 'flex',
+                  displayType : settings.useFlex
+                    ? 'flex'
+                    : 'block',
                   animation   : settings.transition + ' out',
                   queue       : false,
                   duration    : module.get.duration(),
@@ -415,6 +427,9 @@ $.fn.dimmer = function(parameters) {
             module.debug('Setting opacity to', opacity);
             $dimmer.css('background-color', color);
           },
+          legacy: function() {
+            $dimmer.addClass(className.legacy);
+          },
           active: function() {
             $dimmer.addClass(className.active);
           },
@@ -444,6 +459,9 @@ $.fn.dimmer = function(parameters) {
               .removeClass(className.active)
             ;
           },
+          legacy: function() {
+            $dimmer.removeClass(className.legacy);
+          },
           dimmed: function() {
             $dimmable.removeClass(className.dimmed);
           },
@@ -657,6 +675,9 @@ $.fn.dimmer.settings = {
   verbose     : false,
   performance : true,
 
+  // whether should use flex layout
+  useFlex     : true,
+
   // name to distinguish between multiple dimmers in context
   dimmerName  : false,
 
@@ -700,6 +721,7 @@ $.fn.dimmer.settings = {
     dimmer     : 'dimmer',
     disabled   : 'disabled',
     hide       : 'hide',
+    legacy     : 'legacy',
     pageDimmer : 'page',
     show       : 'show'
   },
diff --git a/src/definitions/modules/dimmer.less b/src/definitions/modules/dimmer.less
index 3e534bc28..fb0ce54c5 100755
--- a/src/definitions/modules/dimmer.less
+++ b/src/definitions/modules/dimmer.less
@@ -113,6 +113,18 @@
            Variations
 *******************************/
 
+
+/*--------------
+    Legacy
+---------------*/
+
+/* Animating / Active / Visible */
+.dimmed.dimmable > .ui.animating.legacy.dimmer,
+.dimmed.dimmable > .ui.visible.legacy.dimmer,
+.ui.active.legacy.dimmer {
+  display: block;
+}
+
 /*--------------
     Alignment
 ---------------*/
diff --git a/src/definitions/modules/modal.js b/src/definitions/modules/modal.js
index b2ccea05e..f281a3b08 100755
--- a/src/definitions/modules/modal.js
+++ b/src/definitions/modules/modal.js
@@ -132,7 +132,7 @@ $.fn.modal = function(parameters) {
             $dimmer = $dimmable.dimmer('get dimmer');
           },
           id: function() {
-            id = (Math.random().toString(16) + '000000000').substr(2,8);
+            id = (Math.random().toString(16) + '000000000').substr(2, 8);
             elementEventNamespace = '.' + id;
             module.verbose('Creating unique id for element', id);
           }
@@ -167,6 +167,9 @@ $.fn.modal = function(parameters) {
         refresh: function() {
           module.remove.scrolling();
           module.cacheSizes();
+          if(!module.can.useFlex()) {
+            module.set.modalOffset();
+          }
           module.set.screenHeight();
           module.set.type();
         },
@@ -212,7 +215,7 @@ $.fn.modal = function(parameters) {
 
         get: {
           id: function() {
-            return (Math.random().toString(16) + '000000000').substr(2,8);
+            return (Math.random().toString(16) + '000000000').substr(2, 8);
           }
         },
 
@@ -322,9 +325,16 @@ $.fn.modal = function(parameters) {
             : function(){}
           ;
           if( module.is.animating() || !module.is.active() ) {
-
             module.showDimmer();
             module.cacheSizes();
+            if(module.can.useFlex()) {
+              module.remove.legacy();
+            }
+            else {
+              module.set.legacy();
+              module.set.modalOffset();
+              module.debug('Using non-flex legacy modal positioning.');
+            }
             module.set.screenHeight();
             module.set.type();
             module.set.clickaway();
@@ -513,6 +523,9 @@ $.fn.modal = function(parameters) {
           active: function() {
             $module.removeClass(className.active);
           },
+          legacy: function() {
+            $module.removeClass(className.legacy);
+          },
           clickaway: function() {
             $dimmer
               .off('click' + elementEventNamespace)
@@ -546,11 +559,13 @@ $.fn.modal = function(parameters) {
           $module.addClass(className.loading);
           var
             scrollHeight = $module.prop('scrollHeight'),
+            modalWidth   = $module.outerWidth(),
             modalHeight  = $module.outerHeight()
           ;
           if(module.cache === undefined || modalHeight !== 0) {
             module.cache = {
               pageHeight    : $(document).outerHeight(),
+              width         : modalWidth,
               height        : modalHeight + settings.offset,
               scrollHeight  : scrollHeight + settings.offset,
               contextHeight : (settings.context == 'body')
@@ -564,6 +579,12 @@ $.fn.modal = function(parameters) {
         },
 
         can: {
+          useFlex: function() {
+            return (settings.useFlex == 'auto')
+              ? settings.detachable && !module.is.ie()
+              : settings.useFlex
+            ;
+          },
           fit: function() {
             var
               contextHeight  = module.cache.contextHeight,
@@ -585,6 +606,13 @@ $.fn.modal = function(parameters) {
           active: function() {
             return $module.hasClass(className.active);
           },
+          ie: function() {
+            var
+              isIE11 = (!(window.ActiveXObject) && 'ActiveXObject' in window),
+              isIE   = ('ActiveXObject' in window)
+            ;
+            return (isIE11 || isIE);
+          },
           animating: function() {
             return $module.transition('is supported')
               ? $module.transition('is animating')
@@ -596,7 +624,7 @@ $.fn.modal = function(parameters) {
           },
           modernBrowser: function() {
             // appName for IE11 reports 'Netscape' can no longer use
-            return !(window.ActiveXObject || "ActiveXObject" in window);
+            return !(window.ActiveXObject || 'ActiveXObject' in window);
           }
         },
 
@@ -628,10 +656,10 @@ $.fn.modal = function(parameters) {
                 debug      : settings.debug,
                 dimmerName : 'modals',
                 closable   : 'auto',
+                useFlex    : module.can.useFlex(),
                 variation  : settings.centered
                   ? false
-                  : 'top aligned'
-                ,
+                  : 'top aligned',
                 duration   : {
                   show     : settings.duration,
                   hide     : settings.duration
@@ -657,6 +685,19 @@ $.fn.modal = function(parameters) {
             }
             $context.dimmer('setting', dimmerSettings);
           },
+          modalOffset: function() {
+            var
+              width = module.cache.width,
+              height = module.cache.height
+            ;
+            $module
+              .css({
+                marginTop: -(height / 2),
+                marginLeft: -(width / 2)
+              })
+            ;
+            module.verbose('Setting modal offset for legacy mode');
+          },
           screenHeight: function() {
             if( module.can.fit() ) {
               $body.css('height', '');
@@ -675,6 +716,9 @@ $.fn.modal = function(parameters) {
             $dimmable.addClass(className.scrolling);
             $module.addClass(className.scrolling);
           },
+          legacy: function() {
+            $module.addClass(className.legacy);
+          },
           type: function() {
             if(module.can.fit()) {
               module.verbose('Modal fits on screen');
@@ -880,6 +924,9 @@ $.fn.modal.settings = {
   name           : 'Modal',
   namespace      : 'modal',
 
+  useFlex        : 'auto',
+  offset         : 0,
+
   silent         : false,
   debug          : false,
   verbose        : false,
@@ -909,7 +956,6 @@ $.fn.modal.settings = {
 
   queue      : false,
   duration   : 500,
-  offset     : 0,
   transition : 'scale',
 
   // padding with edge of page
@@ -949,6 +995,7 @@ $.fn.modal.settings = {
     animating  : 'animating',
     blurring   : 'blurring',
     inverted   : 'inverted',
+    legacy     : 'legacy',
     loading    : 'loading',
     scrolling  : 'scrolling',
     undetached : 'undetached'
diff --git a/src/definitions/modules/modal.less b/src/definitions/modules/modal.less
index 6f0236ce7..03e12b954 100755
--- a/src/definitions/modules/modal.less
+++ b/src/definitions/modules/modal.less
@@ -23,6 +23,7 @@
 *******************************/
 
 .ui.modal {
+  position: absolute;
   display: none;
   z-index: @zIndex;
   text-align: left;
@@ -309,6 +310,13 @@
   color: @basicInvertedModalHeaderColor;
 }
 
+/* Resort to margin positioning if legacy */
+.ui.legacy.modal,
+.ui.legacy.page.dimmer > .ui.modal {
+  top: 50%;
+  left: 50%;
+}
+
 /* Tablet and Mobile */
 @media only screen and (max-width : @largestTabletScreen) {
   .ui.basic.modal > .close {