selecting a word stem filter now also highlights the stem in the current word, to make it clear it is on

src/io/github/sspanak/tt9/ime/TraditionalT9.java

@@ -146,20 +146,25 @@ public class TraditionalT9 extends KeyPadHandler {
 	protected boolean onUp() {
 		if (previousSuggestion()) {
 			mInputMode.setWordStem(mLanguage, mSuggestionView.getCurrentSuggestion(), true);
+			setComposingTextWithWordStemIndication(mSuggestionView.getCurrentSuggestion());
 			return true;
 		}
 
 		return false;
 	}
+
+
 	protected boolean onDown() {
 		if (nextSuggestion()) {
 			mInputMode.setWordStem(mLanguage, mSuggestionView.getCurrentSuggestion(), true);
+			setComposingTextWithWordStemIndication(mSuggestionView.getCurrentSuggestion());
 			return true;
 		}
 
 		return false;
 	}
 
+
 	protected boolean onLeft() {
 		if (mInputMode.clearWordStem()) {
 			mInputMode.loadSuggestions(handleSuggestionsAsync, mLanguage, getComposingText());
@@ -170,6 +175,7 @@ public class TraditionalT9 extends KeyPadHandler {
 		return true;
 	}
 
+
 	protected boolean onRight(boolean repeat) {
 		String filter = repeat ? mSuggestionView.getSuggestion(1) : getComposingText();
 
@@ -182,6 +188,7 @@ public class TraditionalT9 extends KeyPadHandler {
 		return true;
 	}
 
+
 	/**
 	 * onNumber
 	 *
@@ -287,7 +294,7 @@ public class TraditionalT9 extends KeyPadHandler {
 		}
 
 		mSuggestionView.scrollToSuggestion(-1);
-		setComposingTextFromCurrentSuggestion();
+		setComposingTextWithWordStemIndication(mSuggestionView.getCurrentSuggestion());
 
 		return true;
 	}
@@ -299,7 +306,7 @@ public class TraditionalT9 extends KeyPadHandler {
 		}
 
 		mSuggestionView.scrollToSuggestion(1);
-		setComposingTextFromCurrentSuggestion();
+		setComposingTextWithWordStemIndication(mSuggestionView.getCurrentSuggestion());
 
 		return true;
 	}
@@ -312,7 +319,7 @@ public class TraditionalT9 extends KeyPadHandler {
 	private void commitCurrentSuggestion(boolean entireSuggestion) {
 		if (!isSuggestionViewHidden() && currentInputConnection != null) {
 			if (entireSuggestion) {
-				setComposingTextFromCurrentSuggestion();
+				setComposingText(mSuggestionView.getCurrentSuggestion());
 			}
 			currentInputConnection.finishComposingText();
 		}
@@ -346,7 +353,7 @@ public class TraditionalT9 extends KeyPadHandler {
 		// for a more intuitive experience.
 		String word = mSuggestionView.getCurrentSuggestion();
 		word = word.substring(0, Math.min(mInputMode.getSequenceLength(), word.length()));
-		setComposingText(word);
+		setComposingTextWithWordStemIndication(word);
 	}
 
 
@@ -391,20 +398,27 @@ public class TraditionalT9 extends KeyPadHandler {
 	}
 
 
-	private void setComposingText(String text) {
+	private void setComposingText(CharSequence text) {
 		if (text != null && currentInputConnection != null) {
 			currentInputConnection.setComposingText(text, 1);
 		}
 	}
 
 
-	private void setComposingTextFromCurrentSuggestion() {
+	private void setComposingTextWithWordStemIndication(CharSequence word) {
-		if (!isSuggestionViewHidden()) {
+		if (mInputMode.getWordStem().length() > 0) {
-			setComposingText(mSuggestionView.getCurrentSuggestion());
+			setComposingText(Util.highlightComposingText(word, 0, mInputMode.getWordStem().length()));
+		} else {
+			setComposingText(word);
 		}
 	}
 
 
+	private void refreshComposingText() {
+		setComposingText(getComposingText());
+	}
+
+
 	private void nextInputMode() {
 		if (mEditing == EDITING_STRICT_NUMERIC || mEditing == EDITING_DIALER) {
 			clearSuggestions();
@@ -416,7 +430,7 @@ public class TraditionalT9 extends KeyPadHandler {
 			ArrayList<String> switchedSuggestions = mInputMode.getSuggestions(mLanguage);
 
 			setSuggestions(switchedSuggestions, mSuggestionView.getCurrentIndex());
-			setComposingText(getComposingText()); // no mistake, this forces the new text case
+			refreshComposingText();
 		}
 		// make "abc" and "ABC" separate modes from user perspective
 		else if (mInputMode.isABC() && mInputMode.getTextCase() == InputMode.CASE_LOWER) {

src/io/github/sspanak/tt9/ime/Util.java

@@ -0,0 +1,33 @@
+package io.github.sspanak.tt9.ime;
+
+import android.graphics.Typeface;
+import android.text.Spannable;
+import android.text.SpannableString;
+import android.text.style.StyleSpan;
+import android.text.style.UnderlineSpan;
+
+import io.github.sspanak.tt9.Logger;
+
+public class Util {
+		public static CharSequence highlightComposingText(CharSequence word, int start, int end) {
+		if (end < start || start < 0) {
+			Logger.w("tt9.util.highlightComposingText", "Cannot highlight invalid composing text range: [" + start + ", " + end + "]");
+			return word;
+		}
+
+		SpannableString styledWord = new SpannableString(word);
+
+		// default underline style
+		styledWord.setSpan(new UnderlineSpan(), 0, word.length(), Spannable.SPAN_INCLUSIVE_INCLUSIVE);
+
+		// highlight the requested range
+		styledWord.setSpan(
+			new StyleSpan(Typeface.BOLD),
+			start,
+			Math.min(word.length(), end),
+			Spannable.SPAN_EXCLUSIVE_EXCLUSIVE
+		);
+
+		return styledWord;
+	}
+}

src/io/github/sspanak/tt9/ime/modes/InputMode.java

@@ -102,6 +102,7 @@ abstract public class InputMode {
 	// Stem filtering.
 	// Where applicable, return "true" if the mode supports it and the operation was possible.
 	public boolean clearWordStem() { return false; }
+	public String getWordStem() { return ""; }
 	public boolean setWordStem(Language language, String stem, boolean exact) { return false; }
 
 	public boolean shouldTrackNumPress() { return true; }

src/io/github/sspanak/tt9/ime/modes/ModePredictive.java

@@ -156,6 +156,14 @@ public class ModePredictive extends InputMode {
 		}
 	}
 
+	/**
+	 * getWordStem
+	 * If "setWordStem()" has accepted a new stem by returning "true", it can be obtained using this.
+	 */
+	public String getWordStem() {
+		return stem;
+	}
+
 
 	/**
 	 * loadSuggestions