Index: src/wp-admin/js/customize-controls.js
===================================================================
--- src/wp-admin/js/customize-controls.js	(revision 37241)
+++ src/wp-admin/js/customize-controls.js	(working copy)
@@ -1783,6 +1783,10 @@
 			control.container.on( 'click keydown', '.remove-button', control.removeFile );
 			control.container.on( 'click keydown', '.remove-button', control.cleanupPlayer );
 
+			// Initialize frame and dropzone.
+			this.initFrame();
+			this.initDropzone();
+
 			// Resize the player controls when it becomes visible (ie when section is expanded)
 			api.section( control.section() ).container
 				.on( 'expanded', function() {
@@ -1803,6 +1807,7 @@
 
 				// Re-render whenever the control's setting changes.
 				control.renderContent();
+				control.initDropzone(); // Must be refreshed whenever the presence of a placeholder may change.
 			} );
 		},
 
@@ -1824,10 +1829,6 @@
 
 			event.preventDefault();
 
-			if ( ! this.frame ) {
-				this.initFrame();
-			}
-
 			this.frame.open();
 		},
 
@@ -1853,6 +1854,46 @@
 			this.frame.on( 'select', this.select );
 		},
 
+		initDropzone: function() {
+			if ( ! this.frame ) {
+				this.initFrame();
+			}
+			
+			if ( ! this.frame.options.uploader ) {
+				return;
+			}
+
+			var uploaderOptions, postID, self = this,
+			    $browser = $( '<a href="#" class="browser" />' ).hide().appendTo( 'body' ),
+			    dropzone = this.container.find( '.placeholder' );
+
+			if ( 0 === dropzone.length ) {
+				// There is currently no placeholder, so there will be no dropzone.
+				$browser.remove();
+				return;
+			}
+
+			uploaderOptions = _.defaults( this.frame.options.uploader || {}, {
+				dropzone: dropzone,
+				browser:  $browser,
+				params:   {}
+			});
+
+			postId = wp.media.view.settings.post.id;
+			if ( postId ) {
+				uploader.params.post_id = postId;
+			}
+			this.dropzoneUploader = new wp.Uploader( uploaderOptions ); // @todo figure out how wp.Uploader works (this currently doesn't work beyond here)
+
+			dropzone.on( 'dropzone:enter', _.bind( function() { 
+				self.container.addClass( 'dropping' );
+			}, this ) );
+			dropzone.on( 'dropzone:leave', _.bind( function() { 
+				self.container.removeClass( 'dropping' );
+			}, this ) );
+
+		},
+
 		/**
 		 * Callback handler for when an attachment is selected in the media modal.
 		 * Gets the selected image information, and sets it within the control.
@@ -3628,6 +3669,44 @@
 			overlay.toggleClass( 'collapsed' ).toggleClass( 'expanded' );
 		});
 
+		// Keyboard shortcuts - esc to exit section/panel.
+		$( 'body' ).on( 'keydown', function( event ) {
+
+			if ( 27 !== event.which ) { // esc
+				return;
+			}
+
+			var foundExpandedContainer = false;
+
+			// Check for expanded sections, return when/if found.
+			api.section.each( function ( section ) {
+				if ( section.expanded() ) {
+					section.collapse();
+					event.preventDefault();
+					foundExpandedContainer = true;
+				}
+			});
+
+			if ( foundExpandedContainer ) {
+				return;
+			}
+
+			// Check for expanded panels, return when/if found.
+			api.panel.each( function ( panel ) {
+				if ( panel.expanded() ) {
+					panel.collapse();
+					event.preventDefault();
+					foundExpandedContainer = true;
+				}
+			});
+
+			if ( foundExpandedContainer ) {
+				return;
+			}
+
+			// Otherwise, we're at the root level, so do nothing.
+		});
+
 		$( '.customize-controls-preview-toggle' ).on( 'click', function() {
 			overlay.toggleClass( 'preview-only' );
 		});