Multiple dialog types can be used simultaneously, like list + message, etc. Resolves #1624.

core/src/main/java/com/afollestad/materialdialogs/internal/main/DialogContentLayout.kt

@@ -80,7 +80,6 @@ internal class DialogContentLayout(
     dialog: MaterialDialog,
     adapter: RecyclerView.Adapter<*>
   ) {
-    check(customView == null) { "Cannot mix list dialogs and custom view dialogs." }
     if (recyclerView == null) {
       recyclerView = inflate(R.layout.md_dialog_stub_recyclerview)
       recyclerView!!.attach(dialog)
@@ -96,7 +95,6 @@ internal class DialogContentLayout(
     scrollable: Boolean
   ) {
     check(customView == null) { "Custom view already set." }
-    check(recyclerView == null) { "Cannot mix list dialogs and custom view dialogs." }
     if (scrollable) {
       addContentScrollView()
       customView = view ?: inflate(res!!, scrollFrame)
@@ -107,12 +105,30 @@ internal class DialogContentLayout(
     }
   }
 
-  fun modifyPadding(
-    top: Int,
-    bottom: Int
+  fun haveMoreThanOneChild() = childCount > 1
+
+  fun modifyFirstAndLastPadding(
+    top: Int = -1,
+    bottom: Int = -1
   ) {
-    getChildAt(0).updatePadding(top = top)
-    getChildAt(childCount - 1).updatePadding(bottom = bottom)
+    if (top != -1) {
+      getChildAt(0).updatePadding(top = top)
+    }
+    if (bottom != -1) {
+      getChildAt(childCount - 1).updatePadding(bottom = bottom)
+    }
+  }
+
+  fun modifyScrollViewPadding(
+    top: Int = -1,
+    bottom: Int = -1
+  ) {
+    if (top != -1) {
+      scrollView.updatePadding(top = top)
+    }
+    if (bottom != -1) {
+      scrollView.updatePadding(bottom = bottom)
+    }
   }
 
   override fun onMeasure(
@@ -122,29 +138,38 @@ internal class DialogContentLayout(
     val specWidth = getSize(widthMeasureSpec)
     val specHeight = getSize(heightMeasureSpec)
 
+    // The ScrollView is the most important child view because it contains main content
+    // like a message.
     scrollView?.measure(
         makeMeasureSpec(specWidth, EXACTLY),
         makeMeasureSpec(specHeight, AT_MOST)
     )
+    val scrollViewHeight = scrollView?.measuredHeight ?: 0
+    val remainingHeightAfterScrollView = specHeight - scrollViewHeight
+    val childCountWithoutScrollView = if (scrollView != null) childCount - 1 else childCount
+
+    if (childCountWithoutScrollView == 0) {
+      // No more children to measure
+      setMeasuredDimension(specWidth, scrollViewHeight)
+      return
+    }
 
-    if (recyclerView != null) {
-      val remainingHeightForList = specHeight - (scrollView?.measuredHeight ?: 0)
-      recyclerView?.measure(
-          makeMeasureSpec(specWidth, EXACTLY),
-          makeMeasureSpec(remainingHeightForList, EXACTLY)
-      )
-    } else if (customView != null) {
-      val remainingHeightForCustomView = specHeight - (scrollView?.measuredHeight ?: 0)
-      customView?.measure(
+    val heightPerRemainingChild = remainingHeightAfterScrollView / childCountWithoutScrollView
+
+    var totalChildHeight = scrollViewHeight
+    for (i in 0 until childCount) {
+      val currentChild = getChildAt(i)
+      if (currentChild.id == scrollView?.id) {
+        continue
+      }
+      currentChild.measure(
           makeMeasureSpec(specWidth, EXACTLY),
-          makeMeasureSpec(remainingHeightForCustomView, AT_MOST)
+          makeMeasureSpec(heightPerRemainingChild, AT_MOST)
       )
+      totalChildHeight += currentChild.measuredHeight
     }
 
-    val scrollWidth = scrollView?.measuredWidth ?: 0
-    val scrollHeight = scrollView?.measuredHeight ?: 0
-
-    setMeasuredDimension(scrollWidth, scrollHeight)
+    setMeasuredDimension(specWidth, totalChildHeight)
   }
 
   override fun onLayout(

core/src/main/java/com/afollestad/materialdialogs/internal/main/DialogTitleLayout.kt

@@ -48,8 +48,7 @@ internal class DialogTitleLayout(
     titleView = findViewById(R.id.md_text_title)
   }
 
-  fun shouldNotBeVisible() =
-    iconView.isNotVisible() && titleView.isNotVisible()
+  fun shouldNotBeVisible() = iconView.isNotVisible() && titleView.isNotVisible()
 
   override fun onMeasure(
     widthMeasureSpec: Int,

core/src/main/java/com/afollestad/materialdialogs/utils/DialogExt.kt

@@ -81,14 +81,16 @@ internal fun MaterialDialog.preShow() {
   this.view.apply {
     if (titleLayout.shouldNotBeVisible() && !customViewNoPadding) {
       // Reduce top and bottom padding if we have no title
-      contentLayout.modifyPadding(
+      contentLayout.modifyFirstAndLastPadding(
           top = frameMarginVerticalLess,
           bottom = frameMarginVerticalLess
       )
     }
     if (getCheckBoxPrompt().isVisible()) {
       // Zero out bottom content padding if we have a checkbox prompt
-      contentLayout.updatePadding(bottom = 0)
+      contentLayout.modifyFirstAndLastPadding(bottom = 0)
+    } else if (contentLayout.haveMoreThanOneChild()) {
+      contentLayout.modifyScrollViewPadding(bottom = frameMarginVerticalLess)
     }
   }
 }

core/src/main/res/values/styles.xml

@@ -47,6 +47,7 @@
   <style name="MD_Dialog_Message">
     <item name="android:layout_width">match_parent</item>
     <item name="android:layout_height">wrap_content</item>
+    <item name="android:layout_gravity">center</item>
     <item name="android:textColor">?android:textColorSecondary</item>
     <item name="android:textSize">@dimen/md_message_textsize</item>
     <item name="android:paddingLeft">@dimen/md_dialog_frame_margin_horizontal</item>
@@ -57,6 +58,7 @@
     <item name="android:layout_width">match_parent</item>
     <item name="android:layout_height">wrap_content</item>
     <item name="android:orientation">vertical</item>
+    <item name="android:gravity">center</item>
   </style>
 
   <style name="MD_ActionButton">

files/src/main/java/com/afollestad/materialdialogs/files/DialogFolderChooserExt.kt

@@ -44,10 +44,13 @@ fun MaterialDialog.folderChooser(
   @StringRes folderCreationLabel: Int? = null,
   selection: FileCallback = null
 ): MaterialDialog {
-  if (allowFolderCreation && !hasWriteStoragePermission()) {
-    throw IllegalStateException("You must have the WRITE_EXTERNAL_STORAGE permission first.")
-  } else if (!hasReadStoragePermission()) {
-    throw IllegalStateException("You must have the READ_EXTERNAL_STORAGE permission first.")
+  if (allowFolderCreation) {
+    check(hasWriteStoragePermission()) {
+      "You must have the WRITE_EXTERNAL_STORAGE permission first."
+    }
+  }
+  check(hasReadStoragePermission()) {
+    "You must have the READ_EXTERNAL_STORAGE permission first."
   }
 
   customView(R.layout.md_file_chooser_base)